Currently, to unselect all selected audio, you press the Home key, which brings the cursor to the beginning of the audio (0 samples along the timeline).
There is a way to unselect all in the “Select” menu, and Ctrl+Shift+A is unused. Maybe, Ctrl+Shift+A can be bound to this menu item by default?
The “Standard” set of presets aims to enable the most commonly used presets, while leaving a reasonable number of keys unbound for user defined (custom) shortcuts.
Huh. I was aware that you could kind of do that, but I never used it because I believed that it move my cursor a few samples to the left or right after deselecting depending on which arrow key I pressed. That’s very interesting, I might start using this in the future.