a11y: menus can't be navigated using the keyboard
Fractal is built on top of the modern technologies where accessibility is a natural feature. Fractal even in its current state of development can be considered to be the most accessible desktop matrix client. It would be nice to document and eventually fix the remaining accessibility related shortcomings so it will fit nicely with other accessible GTK3 apps.
There are some menu buttons such as the menu with the Logout item and the menu with Room details items. When these menus are shown it should be possible to navigate over the corresponding menu items using the keyboard. If this is GTK menu perhaps it would be enough to set initial focus to the first item once the menu is shown.