Closing window rather than withdraw TCL

Question

I am using a graphic user interface builder for Tcl/Tk called "GUI Builder (Komodo Pro)". I have built three different windows that will each be opened after the respective button is clicked. I have managed to get the windows to open and "withdraw", but the process remains open in the background. If the user opens enough windows the program will crash due to the large number of windows.

My question is how can I get the window to fully close, instead of withdraw, thereby save some of the computers memory and process power?

Answer 1

When you click on the window manager close button for a window (which varies a bit in style, but is often a red “X”) Tk ends up receiving a WM_DELETE_WINDOW protocol event (non-X11 platforms are translated to this inside the lower levels of Tk). Tk then responds to this for that window in “the appropriate way”.

By default, windows are destroyed when a WM_DELETE_WINDOW is sent to them; this is the right thing to do in the simple case. You can also explicitly enable this by doing:

wm protocol $toplevel WM_DELETE_WINDOW [list destroy $toplevel]

You wouldn't normally bother with that; the default (which is what happens when you've got an empty handler) has the same effect.

Alternatively, you can make the window withdraw ( wm withdraw $toplevel instead of destroy $toplevel ) or iconify ( wm iconify $toplevel ) or even pop up a dialog to check whether the user is really sure about that.

Tk-enabled applications normally exit once they enter the main event loop with all toplevel windows are closed. In the simplest case (only one Tcl interpreter with Tk loaded) this is the same as saying that the application stops once the . window is destroyed. However, I'm not entirely sure if this is true if you run the Tk application in tclsh by doing package require Tk (there's magic in the code to integrate Tcl and Tk). The best way to find out whether things go away right is to test for yourself; it should only take a moment…