indexing
	description: "[
		Interactive vertical scrolling widget.
	]"
	legal: "See notice at end of class."
	appearance: "[
		+-+
		|^|
		|-|
		| |
		|_|
		|#|
		|-|
		|_|
		|V|
		+-+
	]"
	status: "See notice at end of class."
	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
	revision: "$Revision: 56675 $"

class interface
	EV_VERTICAL_SCROLL_BAR

create 
	default_create
			-- Standard creation procedure.
			-- (from EV_ANY)
		require -- from  ANY
			True
		ensure then -- from EV_ANY
			is_coupled: implementation /= Void
			is_initialized: is_initialized
			default_create_called_set: default_create_called
			is_in_default_state: is_in_default_state

	make_with_value_range (a_value_range: INTEGER_INTERVAL)
			-- Create and assign `a_value_range' to value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			a_value_range_not_void: a_value_range /= Void
			a_value_range_not_empty: not a_value_range.is_empty

feature -- Access

	accept_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.accept_cursor

	actual_drop_target_agent: FUNCTION [ANY, TUPLE [INTEGER_32, INTEGER_32], EV_ABSTRACT_PICK_AND_DROPABLE]
			-- Overrides default drop target on a certain position.
			-- If `Void', `Current' will use the default drop target.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.actual_drop_target_agent

	background_color: EV_COLOR
			-- Color displayed behind foreground features.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.background_color)

	data: ANY
			-- Arbitrary user data may be stored here.
			-- (from EV_ANY)

	default_key_processing_handler: PREDICATE [ANY, TUPLE [EV_KEY]] assign set_default_key_processing_handler
			-- Agent used to determine whether the default key processing should occur for Current.
			-- If agent returns True then default key processing continues as normal, False prevents
			-- default key processing from occurring.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.default_key_processing_handler

	deny_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that does not accept pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.deny_cursor

	foreground_color: EV_COLOR
			-- Color of foreground features like text.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.foreground_color)

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	help_context: FUNCTION [ANY, TUPLE, EV_HELP_CONTEXT]
			-- Agent that evaluates to help context sent to help engine when help is requested
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_HELP_CONTEXTABLE
			bridge_ok: Result = implementation.help_context

	frozen id_object (an_id: INTEGER_32): IDENTIFIED
			-- Object associated with `an_id' (void if no such object)
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			consistent: Result = Void or else Result.object_id = an_id

	leap: INTEGER_32
			-- Size of change made by leap_forward or leap_backward.
			-- Default: 10
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			bridge_ok: Result = implementation.leap

	frozen object_id: INTEGER_32
			-- Unique for current object in any given session
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			valid_id: id_object (Result) = Current

	parent: EV_CONTAINER
			-- Contains `Current'.
			-- (from EV_WIDGET)
		require -- from EV_CONTAINABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_WIDGET
			bridge_ok: Result = implementation.parent

	pebble: ANY
			-- Data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble

	pebble_function: FUNCTION [ANY, TUPLE, ANY]
			-- Returns data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_function

	pebble_positioning_enabled: BOOLEAN
			-- If `True' then pick and drop start coordinates are
			-- pebble_x_position, pebble_y_position.
			-- If `False' then pick and drop start coordinates are
			-- the pointer coordinates.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_positioning_enabled

	pebble_x_position: INTEGER_32
			-- Initial x position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_x_position

	pebble_y_position: INTEGER_32
			-- Initial y position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_y_position

	pointer_position: EV_COORDINATE
			-- Position of the screen pointer relative to `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_show_requested: is_show_requested

	pointer_style: EV_POINTER_STYLE
			-- Cursor displayed when pointer is over this widget.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	real_target: EV_DOCKABLE_TARGET
			-- `Result' is target used during a dockable transport if
			-- mouse pointer is above `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.real_target

	step: INTEGER_32
			-- Size of change made by step_forward or step_backward.
			-- Default: 1
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			bridge_ok: Result = implementation.step

	target_name: STRING_GENERAL
			-- Optional textual name describing `Current' pick and drop hole.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)

	tooltip: STRING_32
			-- Tooltip displayed on `Current'.
			-- If `Result' is empty then no tooltip displayed.
			-- (from EV_TOOLTIPABLE)
		require -- from EV_TOOLTIPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_TOOLTIPABLE
			bridge_ok: equal (Result, implementation.tooltip)
			not_void: Result /= Void
			cloned: Result /= implementation.tooltip

	value: INTEGER_32
			-- Current position within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			bridge_ok: Result = implementation.value

	value_range: INTEGER_INTERVAL
			-- Range of value.
			-- Default: 0 |..| 100
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			bridge_ok: Result /= Void and then Result.is_equal (implementation.value_range)
	
feature -- Measurement

	screen_x: INTEGER_32
			-- Horizontal offset relative to left of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_x

	screen_y: INTEGER_32
			-- Vertical offset relative to top of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_y
	
feature -- Comparison

	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies some.same_type (other)
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result

	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of `other' (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	has_capture: BOOLEAN
			-- Does widget have capture?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_capture

	has_focus: BOOLEAN
			-- Does widget have the keyboard focus?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_focus

	is_displayed: BOOLEAN
			-- Is `Current' visible on the screen?
			-- `True' when show requested and parent displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_displayed

	is_dockable: BOOLEAN
			-- Is `Current' dockable?
			-- If `True', then `Current' may be dragged
			-- from its current parent. 
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_dockable

	is_external_docking_enabled: BOOLEAN
			-- Is `Current' able to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport?
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_external_docking_enabled

	is_external_docking_relative: BOOLEAN
			-- Will dockable dialog displayed when `Current' is docked externally
			-- be displayed relative to parent window of `Current'?
			-- Otherwise displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_external_docking_relative

	is_sensitive: BOOLEAN
			-- Is object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			bridge_ok: Result = implementation.user_is_sensitive

	is_show_requested: BOOLEAN
			-- Will `Current' be displayed when its parent is?
			-- See also is_displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_show_requested

	mode_is_drag_and_drop: BOOLEAN
			-- Is the user interface mode drag and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_drag_and_drop

	mode_is_pick_and_drop: BOOLEAN
			-- Is the user interface mode pick and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_pick_and_drop

	mode_is_target_menu: BOOLEAN
			-- Is the user interface mode a pop-up menu of targets?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_target_menu

	proportion: REAL_32
			-- Relative position of value in value_range.
			-- Range: [0, 1]. Default: 0.0
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			bridge_ok: Result = implementation.proportion

	real_source: EV_DOCKABLE_SOURCE
			-- `Result' is source to be dragged
			--  when a docking drag occurs on `Current'.
			-- If `Void', `Current' is dragged.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.real_source

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of `other'?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
	
feature -- Status setting

	center_pointer
			-- Position screen pointer over center of `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	disable_capture
			-- Disable grab of all user input events.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			not_has_capture: not has_capture

	disable_dockable
			-- Ensure `Current' is not dockable.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			not_is_dockable: not is_dockable

	disable_external_docking
			-- Assign `False' to is_external_docking_enabled.
			-- Forbid `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE
			not_externally_dockable: not is_external_docking_enabled

	disable_external_docking_relative
			-- Assign `False' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE
			external_docking_not_relative: not is_external_docking_relative

	disable_pebble_positioning
			-- Assign `False' to pebble_positioning_enabled.
			-- The pick and drop will start at the pointer position.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: not pebble_positioning_enabled

	disable_sensitive
			-- Make object non-sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_unsensitive: not is_sensitive

	enable_capture
			-- Grab all user input events (mouse and keyboard).
			-- disable_capture must be called to resume normal input handling.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
		ensure -- from EV_WIDGET
			has_capture: has_capture

	enable_dockable
			-- Ensure `Current' is dockable.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			is_dockable: is_dockable

	enable_external_docking
			-- Assign `True' to is_external_docking_enabled.
			-- Allows `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE
			is_externally_dockable: is_external_docking_enabled

	enable_external_docking_relative
			-- Assign `True' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed relative to the top level window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE
			external_docking_not_relative: is_external_docking_relative

	enable_pebble_positioning
			-- Assign `True' to pebble_positioning_enabled.
			-- Use pebble_x_position and pebble_y_position as the initial coordinates
			-- for the pick and drop in pixels relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: pebble_positioning_enabled

	enable_sensitive
			-- Make object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_sensitive: (parent = Void or parent_is_sensitive) implies is_sensitive

	hide
			-- Request that `Current' not be displayed even when its parent is.
			-- If successful, make is_show_requested `False'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	leap_backward
			-- Decrement value by leap if within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			decremented: value = value_range.lower.max (old value - leap)

	leap_forward
			-- Increment value by leap if within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			incremented: value = value_range.upper.min (old value + leap)

	remove_default_key_processing_handler
			-- Ensure default_key_processing_handler is Void.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			default_key_processing_handler_removed: default_key_processing_handler = Void

	remove_pebble
			-- Make pebble `Void' and pebble_function `Void,
			-- Removing transport.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_removed: pebble = Void and pebble_function = Void

	remove_real_source
			-- Ensure real_source is `Void'.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			real_source_void: real_source = Void

	remove_real_target
			-- Ensure real_target is `Void'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			real_target_void: real_target = Void

	set_accept_cursor (a_cursor: like accept_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			accept_cursor_assigned: accept_cursor.is_equal (a_cursor)

	set_actual_drop_target_agent (an_agent: like actual_drop_target_agent)
			-- Assign `an_agent' to actual_drop_target_agent.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			an_agent_not_void: an_agent /= Void
		ensure -- from EV_WIDGET
			assigned: actual_drop_target_agent = an_agent

	set_default_colors
			-- Set foreground and background color to their default values.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed

	set_default_key_processing_handler (a_handler: like default_key_processing_handler)
			-- Assign default_key_processing_handler to `a_handler'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	set_deny_cursor (a_cursor: like deny_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is not
			-- over a valid target.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			deny_cursor_assigned: deny_cursor.is_equal (a_cursor)

	set_drag_and_drop_mode
			-- Set user interface mode to drag and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			drag_and_drop_set: mode_is_drag_and_drop

	set_focus
			-- Grab keyboard focus.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
			is_sensitive: is_sensitive

	set_pebble (a_pebble: like pebble)
			-- Assign `a_pebble' to pebble.
			-- Overrides set_pebble_function.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_pebble_not_void: a_pebble /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_assigned: pebble = a_pebble

	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
			-- Set `a_function' to compute pebble.
			-- It will be called once each time a pick occurs, the result
			-- will be assigned to pebble for the duration of transport.
			-- When a pick occurs, the pick position in widget coordinates,
			-- <<x, y>> in pixels, is passed.
			-- To handle this data use `a_function' of type
			-- FUNCTION [ANY, TUPLE [INTEGER, INTEGER], ANY] and return the
			-- pebble as a function of x and y.
			-- Overrides set_pebble.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_function_not_void: a_function /= Void
			a_function_takes_two_integer_open_operands: a_function.valid_operands ([1, 1])
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_function_assigned: pebble_function = a_function

	set_pebble_position (a_x, a_y: INTEGER_32)
			-- Set the initial position for pick and drop
			-- Coordinates are in pixels and are relative to position of `Current'.
			-- Pebble_positioning_enabled must be `True' for the position to be used,
			-- use enable_pebble_positioning.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_position_assigned: pebble_x_position = a_x and pebble_y_position = a_y

	set_pick_and_drop_mode
			-- Set user interface mode to pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pick_and_drop_set: mode_is_pick_and_drop

	set_proportion (a_proportion: REAL_32)
			-- Move value to `a_proportion' within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
			a_proportion_within_range: a_proportion >= 0 and a_proportion <= 1

	set_real_source (dockable_source: EV_DOCKABLE_SOURCE)
			-- Assign `dockable_source' to real_source.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
			dockable_source_not_void: dockable_source /= Void
			dockable_source_is_parent_recursive: source_has_current_recursive (dockable_source)
		ensure -- from EV_DOCKABLE_SOURCE
			real_source_assigned: real_source = dockable_source

	set_real_target (a_target: EV_DOCKABLE_TARGET)
			-- Assign `a_target' to real_target.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			target_not_void: a_target /= Void
		ensure -- from EV_WIDGET
			assigned: real_target = a_target

	set_target_menu_mode
			-- Set user interface mode to pop-up menu of targets.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			target_menu_mode_set: mode_is_target_menu

	set_target_name (a_name: STRING_GENERAL)
			-- Assign `a_name' to target_name.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_name_not_void: a_name /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			target_name_assigned: a_name /= target_name and a_name.is_equal (target_name)

	show
			-- Request that `Current' be displayed when its parent is.
			-- `True' by default.
			-- If successful, make is_show_requested `True'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	step_backward
			-- Decrement value by step if within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			decremented: value = value_range.lower.max (old value - step)

	step_forward
			-- Increment value by step if within value_range.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
		ensure -- from EV_GAUGE
			incremented: value = value_range.upper.min (old value + step)
	
feature -- Element change

	remove_help_context
			-- Remove key press action associated with `EV_APPLICATION.help_key'.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			help_context_not_void: help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE
			no_help_context: help_context = Void

	remove_tooltip
			-- Make tooltip empty.
			-- (from EV_TOOLTIPABLE)
		require -- from EV_TOOLTIPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_TOOLTIPABLE
			tooltip_removed: tooltip.is_empty

	set_background_color (a_color: like background_color)
			-- Assign `a_color' to background_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE
			background_color_assigned: background_color.is_equal (a_color)

	set_data (some_data: like data)
			-- Assign `some_data' to data.
			-- (from EV_ANY)
		require -- from EV_ANY
			not_destroyed: not is_destroyed
		ensure -- from EV_ANY
			data_assigned: data = some_data

	set_foreground_color (a_color: like foreground_color)
			-- Assign `a_color' to foreground_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE
			foreground_color_assigned: foreground_color.is_equal (a_color)

	set_help_context (an_help_context: like help_context)
			-- Assign `an_help_context' to help_context.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			an_help_context_not_void: an_help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE
			help_context_assigned: help_context.is_equal (an_help_context)

	set_leap (a_leap: INTEGER_32)
			-- Assign `a_leap' to leap.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
			a_leap_positive: a_leap > 0
		ensure -- from EV_GAUGE
			a_leap_assigned: leap = a_leap

	set_minimum_height (a_minimum_height: INTEGER_32)
			-- Set `a_minimum_height' in pixels to minimum_height.
			-- If height is less than `a_minimum_height', resize.
			-- From now, minimum_height is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET
			minimum_height_assigned: minimum_height = a_minimum_height
			minimum_height_set_by_user_set: minimum_height_set_by_user

	set_minimum_size (a_minimum_width, a_minimum_height: INTEGER_32)
			-- Assign `a_minimum_height' to minimum_height
			-- and `a_minimum_width' to minimum_width in pixels.
			-- If width or height is less than minimum size, resize.
			-- From now, minimum size is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width >= 0
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width
			minimum_height_assigned: minimum_height = a_minimum_height
			minimum_height_set_by_user_set: minimum_height_set_by_user
			minimum_width_set_by_user_set: minimum_width_set_by_user

	set_minimum_width (a_minimum_width: INTEGER_32)
			-- Assign `a_minimum_width' in pixels to minimum_width.
			-- If width is less than `a_minimum_width', resize.
			-- From now, minimum_width is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width >= 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width
			minimum_width_set_by_user_set: minimum_width_set_by_user

	set_pointer_style (a_cursor: like pointer_style)
			-- Assign `a_cursor' to pointer_style.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_WIDGET
			pointer_style_assigned: pointer_style.is_equal (a_cursor)

	set_step (a_step: INTEGER_32)
			-- Assign `a_step' to step.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
			a_step_positive: a_step > 0
		ensure -- from EV_GAUGE
			a_step_assigned: step = a_step

	set_tooltip (a_tooltip: STRING_GENERAL)
			-- Assign `a_tooltip' to tooltip.
			-- (from EV_TOOLTIPABLE)
		require -- from EV_TOOLTIPABLE
			not_destroyed: not is_destroyed
			tooltip: a_tooltip /= Void
		ensure -- from EV_TOOLTIPABLE
			tooltip_assigned: tooltip.is_equal (a_tooltip)
			cloned: tooltip /= a_tooltip

	set_value (a_value: INTEGER_32)
			-- Assign `a_value' to value.
			-- (from EV_GAUGE)
		require -- from EV_GAUGE
			not_destroyed: not is_destroyed
			value_in_range: value_range.has (a_value)
		ensure -- from EV_GAUGE
			a_value_assigned: value = a_value
	
feature -- Duplication

	copy (other: like Current)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from EV_ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

	frozen deep_copy (other: like Current)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: like Current)
			-- Copy every field of `other' onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: like Current
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: like Current
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	frozen default: like Current
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)

	refresh_now
			-- Force an immediate redraw of `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
	
feature -- Command

	destroy
			-- Destroy underlying native toolkit object.
			-- Render `Current' unusable.
			-- (from EV_ANY)
		ensure -- from EV_ANY
			is_destroyed: is_destroyed
	
feature -- Contract support

	parent_of_source_allows_docking: BOOLEAN
			-- Does parent of source to be transported
			-- allow current to be dragged out? (See real_source)
			-- Not all Vision2 containers are currently supported by this
			-- mechanism, only descendents of EV_DOCKABLE_TARGET
			-- are supported.
			-- (from EV_DOCKABLE_SOURCE)

	source_has_current_recursive (source: EV_DOCKABLE_SOURCE): BOOLEAN
			-- Does `source' recursively contain `Current'?
			-- As seen by parenting structure.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			source_not_void: source /= Void
	
feature -- Event handling

	change_actions: EV_VALUE_CHANGE_ACTION_SEQUENCE
			-- Actions to be performed when value changes.
			-- (from EV_GAUGE_ACTION_SEQUENCES)
		ensure -- from EV_GAUGE_ACTION_SEQUENCES
			not_void: Result /= Void

	conforming_pick_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when a pebble that fits here is picked.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	dock_ended_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed after a dock completes from `Current'.
			-- Either to a dockable target or a dockable dialog.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES
			not_void: Result /= Void

	dock_started_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when a dockable source is dragged.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES
			not_void: Result /= Void

	drop_actions: EV_PND_ACTION_SEQUENCE
			-- Actions to be performed when a pebble is dropped here.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	focus_in_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is gained.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	focus_out_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is lost.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_press_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_press_string_actions: EV_KEY_STRING_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard press generates a displayable character.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_release_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	mouse_wheel_actions: EV_INTEGER_ACTION_SEQUENCE
			-- Actions to be performed when mouse wheel is rotated.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pick_actions: EV_PND_START_ACTION_SEQUENCE
			-- Actions to be performed when pebble is picked up.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	pick_ended_actions: EV_PND_FINISHED_ACTION_SEQUENCE
			-- Actions to be performed when a transport from `Current' ends.
			-- If transport completed successfully, then event data
			-- is target. If cancelled, then event data is Void.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_button_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_button_release_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_double_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer is double clicked.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_enter_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer enters widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_leave_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer leaves widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_motion_actions: EV_POINTER_MOTION_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer moves.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	resize_actions: EV_GEOMETRY_ACTION_SEQUENCE
			-- Actions to be performed when size changes.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void
	
feature -- Measurement 

	height: INTEGER_32
			-- Vertical size in pixels.
			-- Same as minimum_height when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.height

	minimum_height: INTEGER_32
			-- Lower bound on height in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_height
			positive_or_zero: Result >= 0

	minimum_width: INTEGER_32
			-- Lower bound on width in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_width
			positive_or_zero: Result >= 0

	width: INTEGER_32
			-- Horizontal size in pixels.
			-- Same as minimum_width when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.width

	x_position: INTEGER_32
			-- Horizontal offset relative to parent x_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.x_position

	y_position: INTEGER_32
			-- Vertical offset relative to parent y_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.y_position
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of tagged_out.
			-- (from ANY)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
feature -- Status Report

	is_destroyed: BOOLEAN
			-- Is `Current' no longer usable?
			-- (from EV_ANY)
		ensure -- from EV_ANY
			bridge_ok: Result = implementation.is_destroyed
	
invariant
		-- from EV_GAUGE
	range_not_void: is_usable implies value_range /= Void
	range_not_empty: is_usable implies not value_range.is_empty
	value_in_range: is_usable implies value_range.has (value)
	step_positive: is_usable implies step > 0
	leap_positive: is_usable implies leap > 0
	change_actions_not_void: is_usable implies change_actions /= Void
	proportion_within_range: is_usable implies proportion >= 0.0 and proportion <= 1.0
	proportion_definition: is_usable implies (value_range.upper = value_range.lower implies proportion = 0.0)
	proportion_correct_value: (is_usable and value_range.upper /= value_range.lower) implies ((value - value_range.lower) / (value_range.upper - value_range.lower)).abs - proportion < delta

		-- from EV_WIDGET
	pointer_position_not_void: is_usable and is_show_requested implies pointer_position /= Void
	is_displayed_implies_show_requested: is_usable and then is_displayed implies is_show_requested
	parent_contains_current: is_usable and then parent /= Void implies parent.has (Current)

		-- from EV_PICK_AND_DROPABLE
	user_interface_modes_mutually_exclusive: mode_is_pick_and_drop.to_integer + mode_is_drag_and_drop.to_integer + mode_is_target_menu.to_integer = 1

		-- from EV_ANY
	is_initialized: is_initialized
	is_coupled: implementation /= Void and then implementation.interface = Current
	default_create_called: default_create_called

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from EV_DOCKABLE_SOURCE
	parent_permits_docking: is_dockable implies parent_of_source_allows_docking

		-- from EV_COLORIZABLE
	background_color_not_void: is_usable implies background_color /= Void
	foreground_color_not_void: is_usable implies foreground_color /= Void

		-- from EV_POSITIONED
	width_not_negative: is_usable implies width >= 0
	height_not_negative: is_usable implies height >= 0
	minimum_width_not_negative: is_usable implies minimum_width >= 0
	minimum_height_not_negative: is_usable implies minimum_height >= 0

indexing
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class EV_VERTICAL_SCROLL_BAR