mpack wrote:Shevchuk wrote:Seems that problem is with guest additions. Without GA it goes fullscreen and back to windowed mode just fine
Not really. There has been a problem of OpenGL drivers tripping over the new hardening features on Windows hosts. There can also be totally unrelated host driver bugs which cause OpenGL problems.
Of course if you don't install the GAs then you don't get graphics acceleration which means it can't fail to load the OpenGL drivers. While the observation is true, it's a poor workaround and not a solution: most will want decent graphics performance.
Could you please try the next test build and confirm if going back from fullscreen mode now works for you? https://www.virtualbox.org/download/testcase/VirtualBox-4.3.19-96797-Linux_amd64.run