Fix popover symbols for X11 apps
Turns out that the symbol submitted from the popover gets applied with the base keymap already (rather than the popovers keymap). This is puzzling as the order of events sent from the OSK and in the compositor looks right (and otherwise likely wouldn't work for electron apps using wayland) but as this only affects X11 don't bother too much.
Also clean up a bit around the edges.
Closes: #22 (closed)