Fix strange memory leaks detected in windows platforms.
Explicitly call delete to destroy widget.
Merge remote-tracking branch 'origin' into fix-graphics-memory-leaks
Merge remote-tracking branch 'origin' into fix-graphics-memory-leaks
Destroy window at the end of the test case.
Remove line break at end of source code.
Remove extraneous link libaries.
Merge pull request #56 from DO-CV/fix-graphics-memory-leaks

[MAINT] Fix graphics memory leaks.