Debugger: Sometimes debugger does not finish cleanly when mixed debugging

Steps to reproduce:

• create a minimal Qt Quick Application [from template, if necessary add some code that can be triggered with a BP]
• start debugger and trigger a bp inside the QML part
• when interrupted switch the perspective to the cpp debugger and hit Stop

Current result:

• debugger stops, but the 'Start debugging' buttons/actions are still disabled
• abort debugger is enabled, but does nothing

Sometimes the above situation can be triggered without switching to the cpp debugger (just by letting the inferior continue and stop the inferior by other interaction (hitting 'Close' of the application or doing it by code: 'Qt.quit() inside the onClicked() handler of a MouseArea...)

Note: happens for cdb and gdb.

Note: as it's now possible to start another debugging session with the button on the debugger toolbar it seems to be not that problematic..

alternative way to reproduce:

• create minimal Qt Quick Application [from template]
• place bp inside main.cpp before loading the QML
• start debugging
• when stopped at the bp, hit the 'Stop' button