Detect key presses when an input method is used

[maltee]

We're currently triggering certain actions for Keys.onPressed in a TextArea. This fails when an input method is used, even though none of the relevant characters go to preeditText (@, #, :). I assume that whatever Keys.onPressed is supposed to detect doesn't pass through an input method.
What the key presses are supposed to be doing is to open a popup from which several options can be selected which will then be entered into the TextArea.

How can I make this work?