The root cause of this problem with openscad is this upstream bug in Qt: https://bugreports.qt.io/browse/QTBUG-95108
The symptoms are that in some keyboard layouts, the Qt::GroupSwitchModifier is handled incorrectly, causing some keys to not respond correctly in certain applications. This bug was introduced in Qt 5.15.5, and has been fixed in Qt 5.15.7. The bug can be reproduced by temporarily switching layout: setxkbmap -model pc105 -layout de -variant neo and starting the "openscad" program; in the editor, the <enter> does not work. I verified that installing libqt5gui5 version 5.15.7+dfsg-1+b1 from experimental fixes the problem. So this bug can be closed when Qt 5.15.7 goes into unstable. - Kristian.
