alt vs MOD1, MOD2, etc

[Skip Montanaro <skip pobox com>]

I'm still fiddling around with interpreting keyboard input.  I have this
little key reader script:

    import gtk

    def check_key(widget, evt):
	print "state (%d, %d) : <" % (evt.state, evt.keyval),
	for i in xrange(21):
	    state = evt.state & 1 << i
	    if state:
		print gtk.GDK.GdkModifierType.names[state],
	print ">", gtk.GDK.GdkKeySym.names[evt.keyval]
	return gtk.TRUE

    def _test():
	window = gtk.GtkWindow(gtk.WINDOW_TOPLEVEL)
	window.set_title("title")
	window.connect("destroy", gtk.mainquit)

	b = gtk.GtkButton(label="Type here")
	b.set_usize(200, 200)
	b.connect("key-press-event", check_key)
	b.connect("clicked", gtk.mainquit)
	window.add(b)
	b.grab_focus()

	window.show_all()
	gtk.mainloop()

    if __name__ == "__main__":
	_test()

which prints out the event's state and keyval, then a printable version of
them.  Output looks like

    state (0, 65513) : < > Alt_L
    state (64, 102) : < MOD4_MASK > f
    state (0, 65514) : < > Alt_R
    state (64, 102) : < MOD4_MASK > f
    state (0, 65407) : < > Num_Lock
    state (16, 102) : < MOD2_MASK > f
    state (16, 65407) : < MOD2_MASK > Num_Lock
    state (0, 102) : < > f

What's confusing me is that the Gtk 2.0 docs say that <alt> is an alias for
<mod1>.  On my laptop at least (Dell 7500 running Mandrake 8.0 and XFree86
4.0.3, patch level 7mdk), I see the following correspondence between keys
and modmask bits:

    Alt_L	 MOD4
    Alt_R	 MOD4
    Num_Lock	 MOD2
    Scroll_Lock	 MOD5

Who's right?  The relevant bit of the docs is in the "Key bindings" section
of

    http://developer.gnome.org/doc/API/2.0/gtk/gtk-resource-files.html

I haven't found anything that generates the other MOD bits on my laptop.
Someone (Sawfish?) intercepts the Windows keypress and pops up a menu.  I
haven't been able to figure out how to turn that off.  Is the correspondence
between keys and mask bits more tenuous than the documentation suggests?  If
so, it looks like I will have to track modifier key presses and maintain my
own modifier key state.

On a side note, are there some publically browsable examples of Gtk rc
files?

Thx,

-- 
Skip Montanaro (skip pobox com)
(847)971-7098