The viibility manager state is changed from various handlers, which are not guaranteed to be reentrant, most notably the Wayland handler for preedit done.
As the state is changed, relevant requests to synchronize user-visible UI are fired from the same handler.
In case of imservice_handle_done, GTK widget show function was being called, which triggered another round of handling Wayland, leading to the done handler being called again, and flaking out.
To solve this, the phase of issuing commands needs to be separate from adjusting desired state. It seems that the easiest solution is to delay the show() and hide() calls into the next GTK main loop spin.
A better solution would probably inject itself directly after the change of desired state, so that *all* the side effects are delayed.
Two variants:
* Czech Standard (= qwertz)
* Czech qwerty
The accented letters layout corresponds to the UCW [1] layout shipped
with xkb, so we follow this precedent.
Like the DE layout, and unlike the US layout, the CZ layout has a
comma key and a narrower space bar. The added comma key also serves as
a visual balance to the added accents key, to keep the spacebar
centered.
The layouts have been tested manually on PinePhone.
[1] c60b77ea51/test/data/symbols/cz (L180)
The builtin file path is embedded in the binary and subject to substitution, which makes it invalid when trying to build a .deb reproducibly.
Out of the two solutions, it's easier to make the change here rather than customize .debu building not to run tests reproducibly.
With the policy being disentangled from application, it becomes testable.
This prepares for moving the entire visibility mechanism to the new class and taking away more pieces of ServerContextService.
In addition, this is a good warmup before trying to implement sizing policy.
The `eek/layersurface.c` file should be excluded because it's an imported, "foreign" source, but clang-tidy doesn't seem to have an annotation for that.
An alternative would have been to exclude it in Meson and do the check there, but that requires clang-tidy, raising the barrier to contribute of Squeekboard even more (it already requires libfeedback, which isn't packaged widely).
