I want main window to "gray, freeze, stop working", when some other window is opened. Is there some default way to do it? Pretty much the same as gtk.Dialog is working.
EDIT: Currently I'm just replacing all contents by a text line, but I guess there should be better way.
You really shouldn't try to make a program become unresponsive.
If what you want to do is stop the user from using the window, make the dialog modal: gtk.Dialog.set_modal(True)
How to freeze/grayish window in pygtk?