    indexing
    	description: "Representation of a row of an EV_GRID"
    	date: "$Date: 2006-08-16 14:21:00 -0700 (Wed, 16 Aug 2006) $"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	revision: "$Revision: 62634 $"

    class interface
    	EV_GRID_ROW

    create {EV_GRID}
    	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

    feature -- Access

    	background_color: EV_COLOR
    			-- Color displayed as background of `Current' except where there are items contained that
    			-- have a non-`Void' background_color. If `Void', background_color of parent is displayed.
    			-- See header of `EV_GRID' for a description of this behavior.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	collapse_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is collapsed.
    			-- (from EV_GRID_ROW_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_ROW_ACTION_SEQUENCES
    			result_not_void: Result /= Void

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

    	deselect_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is deselected.
    			-- (from EV_GRID_ROW_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_ROW_ACTION_SEQUENCES
    			result_not_void: Result /= Void

    	expand_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is expanded.
    			-- (from EV_GRID_ROW_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_ROW_ACTION_SEQUENCES
    			result_not_void: Result /= Void

    	foreground_color: EV_COLOR
    			-- Color displayed for foreground features of `Current' except where there are items contained that
    			-- have a non-`Void' foreground_color. If `Void', foreground_color of parent is displayed.
    			-- See header of `EV_GRID' for a description of this behavior.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	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)

    	has_subrow (a_row: EV_GRID_ROW): BOOLEAN
    			-- Is `a_row' a child of Current?
    		require
    			not_destroyed: not is_destroyed
    			a_row_not_void: a_row /= Void
    			is_parented: parent /= Void
    		ensure
    			has_subrow_same_parent: Result implies ((a_row.parent /= Void and parent /= Void) and then a_row.parent = parent)

    	height: INTEGER_32
    			-- Height of `Current' when displayed in a parent
    			-- that has `is_row_height_fixed' set to `False'.
    			-- Note that height is ignored if the parent has
    			-- `is_row_height_fixed' set to `True' and then all rows
    			-- are displayed with identical heights set to `parent.row_height'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_not_negative: Result >= 0

    	index_of_first_item: INTEGER_32
    			-- Return the index of the first non `Void' item within `Current'
    			-- or 0 if none.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			valid_result: Result >= 0 and Result <= count

    	is_expandable: BOOLEAN
    			-- May `Current' be expanded?
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	is_expanded: BOOLEAN
    			-- Are subrows of `Current' displayed?
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	is_part_of_tree_structure: BOOLEAN
    			-- Is `Current' part of a tree structure within `parent_i'?
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_valid: Result = (parent_row /= Void or else subrow_count > 0)

    	is_show_requested: BOOLEAN
    			-- May `Current' be displayed?
    			-- Will return `False' if hide has been called on `Current'.
    			-- A row that is_show_requested does not necessarily have to be visible on screen at that particular time.
    			-- For example, its parent_row (if any) may not be expanded or visible, or the position of `Current' may not
    			-- be within the visible area of parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	item (i: INTEGER_32): EV_GRID_ITEM
    			-- Item at `i'-th column, Void if none.
    		require
    			not_destroyed: not is_destroyed
    			i_within_bounds: i > 0 and i <= count
    			is_parented: parent /= Void

    	parent: EV_GRID
    			-- Grid to which current row belongs.
    		require
    			not_destroyed: not is_destroyed

    	parent_row: EV_GRID_ROW
    			-- Parent row of Current if any, Void otherwise.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_void_when_tree_node_enabled: (parent = Void) or (parent /= Void and then not parent.is_tree_enabled) implies Result = Void
    			has_parent: Result /= Void implies Result.has_subrow (Current)

    	parent_row_root: EV_GRID_ROW
    			-- Parent row which is the root of the tree structure
    			-- in which `Current' is contained. May be `Current' if
    			-- `Current' is the root node of a tree structure.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_consistent_with_parent_tree_properties: (parent = Void or else not parent.is_tree_enabled) = (Result = Void)

    	select_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is selected.
    			-- (from EV_GRID_ROW_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_ROW_ACTION_SEQUENCES
    			result_not_void: Result /= Void

    	selected_items: ARRAYED_LIST [EV_GRID_ITEM]
    			-- All items selected in `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_not_void: Result /= Void
    			valid_count: Result.count <= count

    	subrow (i: INTEGER_32): EV_GRID_ROW
    			-- `i'-th child of Current.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			i_positive: i > 0
    			i_less_than_subrow_count: i <= subrow_count
    		ensure
    			subrow_not_void: Result /= Void
    			subrow_valid: (Result.parent /= Void) and then has_subrow (Result) and then Result.parent_row = Current

    	virtual_y_position: INTEGER_32
    			-- Vertical offset of `Current' in relation to the
    			-- the virtual area of parent grid in pixels.
    			-- `Result' is 0 if parent is `Void'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			parent_void_implies_result_zero: parent = Void implies Result = 0

    	virtual_y_position_unlocked: INTEGER_32
    			-- Vertical offset of unlocked position of `Current', in relation to the
    			-- virtual area of parent grid in pixels.
    			-- If not is_locked, then virtual_y_position = `unlocked_virtual_y_position'.
    			-- If is_locked then `Result' is the "shadow" position where the row would
    			-- be if not locked.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			parent_void_implies_result_zero: parent = Void implies Result = 0

    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

    	count: INTEGER_32
    			-- Number of items in current.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			count_not_negative: count >= 0

    	index: INTEGER_32
    			-- Position of Current in parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			index_positive: Result > 0
    			index_less_than_row_count: Result <= parent.row_count

    	is_locked: BOOLEAN
    			-- Is `Current' locked so that it no longer scrolls?

    	is_selectable: BOOLEAN
    			-- May enable_select be called?
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed

    	is_selected: BOOLEAN
    			-- Is selected?
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed
    		ensure -- from EV_SELECTABLE
    			bridge_ok: is_selectable implies Result = implementation.is_selected

    	locked_position: INTEGER_32
    			-- Locked position of `Current' from top edge of viewable area of parent.
    			-- `Result' is 0 if not is_locked.
    		ensure
    			not_locked_implies_result_zero: not is_locked implies Result = 0

    	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))

    	subrow_count: INTEGER_32
    			-- Number of children.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			subrow_count_non_negative: subrow_count >= 0
    			subrow_count_in_range: subrow_count <= (parent.row_count - index)

    	subrow_count_recursive: INTEGER_32
    			-- Number of child rows and their child rows recursively.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			subrow_count_recursive_greater_or_equal_to_subrow_count: subrow_count_recursive >= subrow_count
    			subrow_count_recursive_in_range: subrow_count_recursive <= (parent.row_count - index)

    feature -- Status setting

    	collapse
    			-- Hide all subrows of `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			not_is_expanded: not is_expanded

    	disable_select
    			-- Deselect the object.
    			-- (from EV_DESELECTABLE)
    		require -- from EV_DESELECTABLE
    			not_destroyed: not is_destroyed
    		ensure -- from EV_DESELECTABLE
    			unselected: not is_selected

    	enable_select
    			-- Make is_selected True.
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed
    			is_selectable: is_selectable
    		ensure -- from EV_SELECTABLE
    			is_selected: is_selected

    	ensure_expandable
    			-- Ensure `Current' displays an expand pixmap to simulate a `row_count' greater than 0.
    			-- May be used for dynamic behavior by filling subrows upon firing of `grid.row_expand_actions'.
    			-- If no items are added to `Current' during the firing of `grid.row_expand_actions' then
    			-- `Current' is no longer expandable. This may be re-instated by calling ensure_expandable again
    			-- from `grid.row_expand_actions'. Note that once a subrow is added to `Current' after a call to
    			-- ensure_expandable, it is no longer be displayed as expandable if all subrows are then removed.
    			-- In this case, you must explicitly call ensure_expandable again after removing all subrows.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    			parent_tree_enabled: parent.is_tree_enabled
    		ensure
    			is_expandable: is_expandable

    	ensure_non_expandable
    			-- Restore expanded state of `Current' after a call to ensure_expandable. Note that if a row
    			-- has one or more subrows, it is always drawn as expanded, hence the "no_subrows_contained" precondition.
    		require
    			not_destroyed: not is_destroyed
    			no_subrows_contained: subrow_count = 0
    			parented: parent /= Void
    		ensure
    			not_is_expandable: not is_expandable

    	ensure_visible
    			-- Ensure `Current' is visible in viewable area of parent.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    		ensure
    			parent_virtual_x_position_unchanged: old parent.virtual_x_position = parent.virtual_x_position
    			to_implement_assertion ("old_is_visible_implies_vertical_position_not_changed")
    			row_visible_when_heights_fixed_in_parent: parent.is_row_height_fixed implies virtual_y_position >= parent.virtual_y_position and virtual_y_position + parent.row_height <= parent.virtual_y_position + (parent.viewable_height).max (parent.row_height)
    			row_visible_when_heights_not_fixed_in_parent: not parent.is_row_height_fixed implies virtual_y_position >= parent.virtual_y_position and virtual_y_position + height <= parent.virtual_y_position + (parent.viewable_height).max (height)

    	expand
    			-- Display all subrows of `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			is_expandable: is_expandable
    		ensure
    			is_expanded: is_expanded or subrow_count = 0

    	hide
    			-- Prevent `Current' from being shown in parent.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    		ensure
    			not_is_show_requested: not is_show_requested

    	lock
    			-- Ensure is_locked is `True'.
    			-- `Current' is locked at it's current vertical offset from
    			-- the top edge of the viewable area of parent.
    		ensure
    			is_locked: is_locked
    			locked_position_set: locked_position = virtual_y_position - parent.virtual_y_position

    	lock_at_position (a_position: INTEGER_32)
    			-- Ensure is_locked is `True' with the vertical offset from
    			-- the top edge of the viewable area of parent set to `a_position'.
    		ensure
    			is_locked: is_locked
    			locked_position_set: locked_position = a_position

    	redraw
    			-- Force all items within `Current' to be re-drawn when next idle.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void

    	set_background_color (a_color: EV_COLOR)
    			-- Set background_color with `a_color'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			background_color_set: background_color = a_color

    	set_foreground_color (a_color: EV_COLOR)
    			-- Set foreground_color with `a_color'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			foreground_color_set: foreground_color = a_color

    	set_height (a_height: INTEGER_32)
    			-- Assign `a_height' to height.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			height_set: height = a_height

    	show
    			-- Ensure `Current' is shown in parent.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    		ensure
    			is_show_requested: is_show_requested

    	toggle
    			-- Change is_selected.
    			-- (from EV_DESELECTABLE)
    		require -- from EV_DESELECTABLE
    			not_is_destroyed: not is_destroyed
    			can_be_selected: not is_selected implies is_selectable
    		ensure -- from EV_DESELECTABLE
    			is_selected_changed: is_selected /= old is_selected

    	unlock
    			-- Ensure is_locked is `False'.
    		ensure
    			not_is_locked: not is_locked

    feature -- Element change

    	add_subrow (a_row: EV_GRID_ROW)
    			-- Make `a_row' a child row of Current.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			a_row_not_void: a_row /= Void
    			a_row_is_parented: a_row.parent /= Void
    			a_row_is_not_current: a_row /= Current
    			a_row_is_not_a_subrow: a_row.parent_row = Void
    			same_parent: a_row.parent = parent
    			parent_enabled_as_tree: parent.is_tree_enabled
    			a_row_is_below_current: a_row.index > index
    			all_rows_between_row_and_current_are_subrows: a_row.index = index + subrow_count_recursive + 1
    			row_not_empty_implies_row_index_of_first_item_greater_or_equal_to_index_of_first_item: a_row.index_of_first_item > 0 implies a_row.index_of_first_item >= index_of_first_item
    		ensure
    			added: a_row.parent_row = Current
    			subrow (subrow_count) = a_row

    	clear
    			-- Remove all items from `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			cleared: index_of_first_item = 0

    	insert_subrow (subrow_index: INTEGER_32)
    			-- Add a new row to parent as a subrow of `Current'
    			-- with index in subrows of `Current' given by `subrow_index'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			parent_enabled_as_tree: parent.is_tree_enabled
    			valid_subrow_index: subrow_index >= 1 and subrow_index <= subrow_count + 1
    		ensure
    			subrow_count_increased: subrow_count = old subrow_count + 1
    			parent_row_count_increased: parent.row_count = old parent.row_count + 1

    	insert_subrows (rows_to_insert, subrow_index: INTEGER_32)
    			-- Add `rows_to_insert' rows to parent as a subrow of `Current'
    			-- with index in subrows of `Current' given by `subrow_index'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			parent_enabled_as_tree: parent.is_tree_enabled
    			rows_to_insert_positive: rows_to_insert >= 1
    			valid_subrow_index: subrow_index >= 1 and subrow_index <= subrow_count + 1
    		ensure
    			subrow_count_increased: subrow_count = old subrow_count + rows_to_insert
    			parent_row_count_increased: parent.row_count = old parent.row_count + rows_to_insert

    	remove_subrow (a_row: EV_GRID_ROW)
    			-- Ensure that `a_row' is no longer a child row of `Current'.
    			-- Does not remove `a_row' from `parent_i'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			a_row_not_void: a_row /= Void
    			a_row_is_parented: a_row.parent /= Void
    			a_row_is_not_current: a_row /= Current
    			a_row_is_a_subrow: a_row.parent_row = Current
    			same_parent: a_row.parent = parent
    			parent_enabled_as_tree: parent.is_tree_enabled
    			row_is_final_subrow_in_tree_structure: a_row.index + a_row.subrow_count_recursive = parent_row_root.index + parent_row_root.subrow_count_recursive
    		ensure
    			removed: a_row.parent_row = Void
    			subrow_count_decreased: subrow_count = old subrow_count - 1

    	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_item (i: INTEGER_32; a_item: EV_GRID_ITEM)
    			-- Set item at `i'-th column to be `a_item'.
    			-- If `a_item' is `Void', the current item (if any) is removed.
    		require
    			not_destroyed: not is_destroyed
    			i_positive: i > 0
    			is_parented: parent /= Void
    			is_index_valid_for_item_insertion_if_subrow: a_item /= Void and then is_part_of_tree_structure implies is_index_valid_for_item_setting_if_tree_node (i)
    			is_index_valid_for_item_removal_if_subrow: a_item = Void and then is_part_of_tree_structure implies is_index_valid_for_item_removal_if_tree_node (i)
    		ensure
    			item_set: item (i) = a_item

    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)

    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

    	is_index_valid_for_item_removal_if_tree_node (a_index: INTEGER_32): BOOLEAN
    			-- May an item be removed from `Current' at index `a_index' if `Current' is a tree node.
    		require
    			is_part_of_tree_structure: is_part_of_tree_structure
    			index_valid: a_index > 0 and then a_index <= count

    	is_index_valid_for_item_setting_if_tree_node (a_index: INTEGER_32): BOOLEAN
    			-- May an item be set in `Current' at index `a_index' if `Current' is a tree node.
    		require
    			is_part_of_tree_structure: is_part_of_tree_structure
    			index_valid: a_index > 0

    feature -- Markers

    	fixme (comment: STRING_8)
    			-- Mark code that has to be "fixed" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    	to_implement (comment: STRING_8)
    			-- Mark code that has to be "implemented" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    	to_implement_assertion (comment: STRING_8): BOOLEAN
    			-- Mark assertion that has to be "implemented" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    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
    	no_subrows_implies_not_expanded: subrow_count = 0 implies not is_expanded
    	tree_disabled_in_parent_implies_no_subrows: parent /= Void and then not parent.is_tree_enabled implies subrow_count = 0
    	virtual_position_and_virtual_position_unlocked_equal_when_not_locked: not is_locked implies virtual_y_position = virtual_y_position_unlocked

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

    		-- from EV_DESELECTABLE
    	not_selectable_therefore_not_selected: not is_selectable implies not is_selected

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

    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_GRID_ROW