Practical Programming in Tcl & Tk, Third Edition

Custom Dialogs

When you create your own dialogs, you need to understand keyboard focus, focus grabs, and how to wait for the user to finish with a dialog. Here is the general structure of your code when creating a dialog:

# Create widgets, then
focus $toplevel
grab $toplevel
tkwait window $toplevel

This sequence of commands directs keyboard focus to the toplevel containing your dialog. The grab forces the user to interact with the dialog before using other windows in your application. The tkwait command returns when the toplevel window is destroyed, and this automatically releases the grab. This assumes that the button commands in the dialog destroy the toplevel. The following sections explain these steps in more detail, and Example 36-1 on ...