Check KeyDown Event Handler Behavior

[y0014984]

At some point of testing with the Gruppe Adler modset I experienced a behavior, when pressing the 'u' key while typing in the armaOS terminal, the Gruppe Adler Group Management interface popped up. Currently I can't reproduce that behavior. But perhaps we need to investigate that.

A possible solution could be to create a display instead on an dialog. I think this way the displayEventHandler of the default display that hosts the dialog would be ignored. Currently the text control of the terminal window uses a controlEventHandler instead of an displayEventHandler.