Debugger: Special handling for e.g. QImage does not work

Steps to reproduce:

• open simple.pro (tests/manual/debugger/simple) use MinGW
• place a breakpoint inside testQImageDisplay() and change the QImage variable display type to be 'Separate Window'
• step 'til leaving the function

Current result:

• no separate window comes up to display the image

Expected result:

• separate window that displays the image comes up and changes while stepping

Note: this works when using MSVC + cdb (with python dumper)

Note: Plotting and displaying strings in a separate window seems to be working as expected - so, this might be only effect displaying QImage/QPixmap..