Use GtkCheckMenuItem for window menu items
Submitted by Mathias Brodala
Assigned to Olivier Fourdan
The three menu items "Always on Top", "Always Below Other Windows" and "Always on Visible Workspace" should really be GtkCheckMenuItems.
This would also eliminate the confusing "Same as Other Windows" menu item. One can impossibly know what shall be the "same as other windows" if he doesn’t remember which menu item this originally was.