Main content is navigateable with a keyboard when sidebar is revealed
When the AdwOverlaySplitView sidebar is revealed, the main content can be navigated and interacted with a keyboard via Tab/Arrow/Enter keys. Instead, the main content should be obscured from the keyboard (as it is with the pointer), so that only the sidebar can be interacted with.
This was worked around in gnome-control-center!2778 (merged) via gnome-control-center@8f2954a3.