If you assign layout switching to Ctrl+Shift, for example, you'll not be able
to use ANY program hotkeys with Ctrl+Shift+[key]. Instead of expected action
you'll get layout switching as soon as you press Ctrl+Shift. Bugreport in
upstream is 6 years old! Here is a bugreport in upstream (there is a patch
attached to it): https://bugs.freedesktop.org/show_bug.cgi?id=865 Here is
direct link to patch: https://bugs.freedesktop.org/attachment.cgi?id=33142
Patch worked for me (I've tested it with xorg-server 1.7.5). Please, include it
in packages. This bug is really annoying.