"When I push the buttons "p","Ctrl" and "g" the answer is "pg". The same result with all other roman letters and the buttons "roman letter", "CtrlGr" and "g",or "roman letter", "p" "Alt" and "g¨. The answer is always ¨roman letterg"
The keyboard: English US international with dead keys. I have not experienced other problems using SMath Studio. I have OS "Linux mint Sarah" updated into "Linux mint Serena".