The only remaining sync call from client to server is now the call that switches a window's backing store. That one actually relies on the synchronization to hand over ownership of the backing stores, so it has to stay synchronous for now.
There was no way to close catdog since it relied on global menus, this adds a context menu for opening the about dialog and quitting. Fixes #7252
This adds helpful speech bubbles to CatDog. CatDog just wants to help, that's all.
