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# 7 User Communication

### Sections

1. Menus in Graphic Sheets
2. Mouse Events
3. Dialogs
4. Popups

XGAP has two main means to communicate with the user. The first is the normal command processing: The user types commands, they are transmitted to GAP, are executed, and produce output, which is displayed in the command window. The second is the mouse and the other parts of the graphical user interface. This latter part can be divided into menus, mouse events, dialogs, and popups.

Menus
  Most of the windows of XGAP have menus. The user can select entries in them and this information is transformed to a function call in GAP. Menu entries can be checked or not, so menus can also display information.

Mouse Events
  A mouse event is the pressing or releasing of a mouse button, together with the position where the mouse pointer is in the exact moment this happens and the state of certain keyboard keys (mainly shift and control). Such events also trigger GAP function calls and the corresponding functions can react on these events and for example wait for others.

Dialogs
  Dialogs are windows which display information and into which the user can enter information for example in form of text fields.

Popups
  Popups are special dialogs where the user can not type text but can only click on certain buttons. XGAP has so called ``text selectors'' which are a convenient construct to display textual information and let the user select parts of it.

Most of those graphical objects have corresponding GAP objects, which are created by constructors and can be used later on by operations.

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