### 6.4 Navigating with hyperlinks

When the Control key is pressed and you start moving the mouse, entities in the editors under the mouse cursor become hyperlinks and the mouse cursor aspect changes.

Left-clicking on a reference to an entity will open a source editor on the declaration of this entity, and left-clicking on an entity declaration will open an editor on the implementation of this entity.

Clicking with the middle button on either a reference to an entity or the declaration of an entity will jump directly to the implementation or type completion) of this entity.

Note that for efficiency, GPS may create hyperlinks for some entities which have no associated cross reference. In this case, clicking will have no effect, even though an hyperlink may have been displayed.

This behavior is controlled by the `Hyper links` preference.