[openbox] Cannot use keyboard sometimes after changing desktops

[Dani]

Dani:
> Windows do get focus and text fields get a flashing text cursor after I
> click on them. They still don't get keystrokes.
> 
> Unfocusing (middle mouse) does not help. Shading, unshading, maximizing
> or changing focus between windows by clicking do not help.
> 
> I noticed that the problem also goes away by doing any of these: moving
> a window, cycling focus with alt and tab keys, showing an OpenBox menu.

Actually the cursor won't always appear / the text fields don't always
get focus.