keyboard grabs and keynav... (bug 77517)

[jacob berkman <jacob ximian com>]

if an app grabs the keyboard, and a user uses the space bar to activate
a button, the focus indicator goes away and the user can no longer
navigate the dialog with the keyboard (at least in the logout dialog).

should gtkbutton restore the previous grab?  should it do something
different?  should the dialog just re-grab after every toggle?

 - jacob