I've got similar problem in 4.6.5:
when launching the program with -force-opengl option, it runs normally; then if I use Alt+Tab to switch to another window, and then switch back, the program window shows all black.
Has this bug been solved please?

Leizhan paper machinery for fiber pulp and waste paper recycling process
product description
paper making machine production line
Waste paper making machine production line
Kraft paper making machine production line
Testliner paper making machine production line
Corrugated paper making machine production line
Fluting paper making machine production line
Coated white board making machine production line
Tissue making machine production line
Toliet paper making machine production line
Culture paper making machine production line
A4 paper making machine production line
Printing and writing paper making machine production line
Napkin paper making machine production line
OCC line
http://www.papermaking-equipment.com/

http://www.papermaking-equipment.com/kraft-paper-making-line/conveying-solution-for-paper-pulp-production-industry/

The problem seems to be that when you activate fullscreen, the previous resolution is used. I made a workaround by detecting max possible resolution, and when Screen.fullscreen is set to true, I force a Screen.SetResolution(maxWidth, maxHeight, true);

Now there's another problem with opengl. It crashes in windowed mode in high resolutions such as 1920x1080. I reported a new bug for this with a reproduction project.

This is supposed to be fixed in 4.6.1 (https://unity3d.com/unity/whats-new/unity-4.6.1), but now instead of some black squares, I have the entire screen black.

This issue does not occur with unity 4.5.0 but with 4.5.3 and later (excluding 5.0)

After minimizing and "reopening" the window, it will display the game correctly.