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## Procedures

When the interface for the application is finished, the functionality must be implemented. The functionality is usually implemented with Tcl/Tk procedures that are called by buttons, bindings etc.. Here, the user's Tcl/Tk

experience is needed (respectively: here he gains Tcl/Tk

experience).

The implementation of the functionality is supported by XF

with special dialogs. These dialogs are activated with the menu items (Programming | Procedures) and (Programming | Commands). They activate dialog windows, where procedures and commands can be created, modified, deleted etc. (see figure ).

Besides the procedures that are written by the user, there exist various special procedures that are used by XF . The procedure dialog only gives access to procedures that the user is allowed to change. The two most important procedures are StartupSrc and EndSrc. To modify these procedures, the menu items (Programming | Startup source) and (Programming | End source) are used.

If the application needs control when the application program is started (e.g. for parsing the argument list or for setting the contents of a list at startup), the code is added to the startup procedure. This code is executed as first source of the complete application.

If the application needs control after the toplevel windows (containing the dialog components) have been displayed (e.g. to initialize widgets with certain values), the code is added to the end procedures.