Arranges for window to be withdrawn from the screen. This causes the window to be unmapped and forgotten about by the window manager. If the window has never been mapped, then this command causes the window to be mapped in the withdrawn state. Not all window managers appear to know how to handle windows that are mapped in the withdrawn state. Note: it sometimes seems to be necessary to withdraw a window and then re-map it (e.g. with wm deiconify) to get some window managers to pay attention to changes in window attributes such as group.
Here's a note on wm withdraw from George Petasis in the comp.lang.tcl newsgroup:
I wouldn't advise you to use "wm withdraw ." on the "." window. Under some window managers (especially under unix...) this will prevent dialogs that have as parent the "." (like error messages) from showing up and block your app. Better to use something like:
wm geometry . 1x1+0+0 wm overrideredirect . 1 wm transient .
You can even send it out of the visible part of the screen, like wm geometry . 1x1+3000+3000
But in any case, do not withdraw it :-)