xkb: wrong KeySym at first start of X

[chris_honschu at gmx.de]

On Thursday, 13. August 2009, Peter Hutterer wrote:
> On Thu, Aug 13, 2009 at 02:48:33AM +0200, chris_honschu at gmx.de wrote:
> > On Thursday, 13. August 2009, Peter Hutterer wrote:
> > > On Tue, Aug 11, 2009 at 04:15:37PM +0200, chris_honschu at gmx.de wrote:
> > > > at the first start and at the very beginning of a running X
> > > > the KeySym changes from a wrong value to the correct
> > > > one.
> > > > Is this a bug? Because thereby my window-manager
> > > > keymappings go wrong.
> > > >
> > > > I have a 'de' (German) keyboard (qwertz).
> > > > For the first ~14k loops of xkeytest the button "y" is
> > > > referred to a 'z':
> > > >
> > > > loop-nr.:0 testing KeyCode=52 -> KeySym 0x7a name=z
> > > > loop-nr.:13906 testing KeyCode=52 -> KeySym 0x79 name=y
> > >
> > > the internal virtual keyboard is initialized with the default layout
> > > ('us'), the physical keyboard with 'de' per your configuration. once
> > > you hit a key on the german layout, this layout it copied over into the
> > > virtual one and the virtual keyboard also has a german layout.
> > > so the change from 'us' to 'de' is not accidental.
> >
> > /tmp/xkeytest:
> > *** date:
> > Tue Aug 11 15:13:51 CEST 2009
> > loop-nr.:0 testing KeyCode=52 -> KeySym 0x7a name=z
> > *** xprop -root | grep XKB
> > _XKB_RULES_NAMES(STRING) = "xorg", "pc105", "de", "", ""
> >
> > I didn't have a look at the sourcecode of xprop but shouldn't it print
> > out a 'us' instead of a 'de' keyboard layout,?
> > So here is a bug in either xprop or in xorg. Am I right?
>
> it's a essentially unfixable problem with the property itself.
>
> http://bugs.freedesktop.org/show_bug.cgi?id=21669
> "we only have one property that stores the XKB RMLVO information and this
> is overwritten by each keyboard on startup. This results in wrong data if
> there's at least two keyboards with different RMLVO settings."

Thanks for your very fast answer. This brings light into the darkness ,-)

I understand: For the window manager that sets the key-mappings very fast at the 
beginning of a more or less starting Xorg it's essential to listen to 
MappingNotify as you kindly explained.

My question is now: Would this MappingNotify report the keysyms in a atomic way 
so that I can rely on that it is a 'de' or 'us' keymap - or would I end up in a 
mess of a combination of both when I parse them?

thanks for your help
 Christoph