Merging branch 'i458'  into 'main'.

See merge request !1345

Merging branch 'i447'  into 'main'.

See merge request !1342

[432-glcontext] MainWindow: Addend bandage fix to keep MainWindow open when the docked OpenGl... (Closes #432)

Merging branch '432-glcontext'  into 'main'.

See merge request !1333

Canvas is not initialized in application start so a window manager like x11 may reopen the mainwindow on gl context switching without this fix.

The behaviour was caused by different surface format / opengl contexts of the QMainWindow instance and the QOpenGLWidget instance of Canvas. In Qt6 it became more complex to quickly share the gl context. Hence we just create a dummy QOpenGLWidget before MainWindow is show to reset it.

Merging branch 'corr_struct'  into 'main'.

See merge request !1341

Merging branch 'rm_SessionItem_SessionModel'  into 'main'.

See merge request !1340

Merging branch 'masks_fix_finish'  into 'main'.

See merge request !1339