vtkRenderer backing store breaks when window unexposed
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
Steps to reproduce:
- Open the attached VTK program (or any other VTK program: just modify it by calling BackingStoreOn() on a renderer).
- Set any other window to be "always on top".
- Move the other window so that it half-covers the VTK window.
- Manipulate the camera in the VTK window, while the other window covers half of it.
- Move the other window away.
Expected results: the image in the VTK window is identical to what it would have been if the other window hadn't been there.
Actual results: the part of the VTK window which was underneath the other window has the "old" image -- that is, exactly the contents which it had before it was covered by the other window.
This is an extreme annoyance in, say, a program with a large render area which uses dialogs: the dialogs create these glitches very often.