Set tkinter top-level window to "always on visible workspace"

[Skip Montanaro]

I have a tkinter app (Ubuntu/X11 env) whose main window should always be
displayed on the currently visible workspace. Is there some way to set that
attribute programmatically? I see that there is a tkinter.Wm class and that
Toplevel widgets have a wm_attributes method, but haven't found any
examples in the library doc or on the wider net which demonstrate control
of this particular window manager interaction. (I don't care about Windows
or Mac, at least for the time being.)

Thx,

Skip