wxMaxima does not close Maxima on closing

[ReneSci]

When starting wxMaxima by opening (double-click) a .wxmx file these processes has been initiated:

After having executed a Maxima function, this is what i running on the PC:

However after closing wxMaxima it still leaves this running and thus preventing a new session:

Afterwards, when re-opening wxMaxima, it refuses to execute any Maxima commands until I manually kills the sbcl.exe previously left behind.

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If I on the other hand just start wxMaxima (with a empty worksheet) this is seen:

Running some Maxima functions does not start any extra sbcl.exe and the whole wxMaxima/Maxima complex shuts down as expected.

Also, if I start wxMaxima and opens a file form within wxMaxima, it also works fine.

Drag and drop also works fine.

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So it seems like the double-click (opening a file on he command line) initiates an extra sbcl.exe where one of them is not being used.

wxMaxima version: 20.01.2-DevelopmentSnapshot
using wxWidgets version: wxWidgets 3.1.3
Maxima version: branch_5_43_base_264_g292ed6cfd
Maxima build date: 2020-01-15 00:05:44
Host type: x86_64-w64-mingw32
System type: Win32 10.0.17134 X86-64
Lisp implementation type: SBCL
Lisp implementation version: 1.4.14
wxMaxima's idea of the directory layout is:
User configuration dir: C:\Users\xxxxxx/maxima/
Help dir: C:\maxima-current\share/doc/wxmaxima

[ReneSci]

No - it still leaves a sbcl.exe behind when closed:

One for each time wxMaxima is opened:

However, now the next session works normally, so the user will not see the sbcl.exe left behind.
And - still this only happens when the windows double-click is used to open a wxmx file.