Shaperilio/qtgui fixes (#13957)...
Shaperilio/qtgui fixes (#13957)
I started using the released version of my `PySide6`-enabling changes
and noted some problems. In this PR, I fix those, and also overall
improve the feedback to the user when a GUI event loop is hooked in:
- Report which event loop is running when using `%gui <some GUI>`; e.g.
`%gui qt` will show `Installed qt6 event loop hook.`
- Report when the event loop is disabled; i.e. `%gui` will show `GUI
event loop hook disabled.` if an event loop hook was installed, or `No
event loop hook running.` if nothing was installed.
- Requesting a second event loop will give the message `Shell is already
running a gui event loop for <some GUI>. Call with no arguments to
disable current loop.`
- Requesting a different version of Qt, i.e. `%gui qt6` followed by
`%gui` followed by `%gui qt5` will show `Cannot switch Qt versions for
this session; will use qt6.` followed by `Installed qt6 event loop
hook.`
(Fixes / improves
#13864)
