Not sending CTRL/ALT/Shift key events (and just setting the modifiers) breaks some applications
Not sending CTRL/ALT/Shift key events and just setting the modifiers breaks some applications. The problem isn't just games that may require these keys to be pressed on their own, but also that some UI applications may track modifiers manually by listening for these key inputs instead. E.g. I use an SDL2 non-game app that does that.
Therefore I suggest that CTRL + ALT events should be toggled along with the buttons being toggled in squeekboard's terminal layout, and a left shift key down event should be sent as soon as a key is typed from the uppercase pane after one from a different pane and key up when vice versa (such that the mere act of toggling through the panes doesn't generate key presses on its own, since I think most users would not expect that).