Steps to repro:

1. Open Unity on Windows;
2. Create new project;
3. Maximize Editor window (make it full-screened);
4. Minimize Editor Window;
4. Double click on attached package in file manager.

Expected result:
Package import window is shown with no errors in console.

Actual result:

2 errors:

' GUI Window tried to begin rendering while something else had not finished rendering! Either you have a recursive OnGUI rendering, or the previous OnGUI did not clean up properly;
and
'Assertion failed: Assertion failed on expression: 'device.IsInsideFrame()'

are shown in the console. See attached video

Regression introduced in Unity 2017.1.0b2.

Notes:
- Reproducible in Unity 2017.1.0b2;
- Not reproducible in 2017.1.0b1, 5.6.0p3, 5.5.2p1;
- Reproducible only on Windows 10;
- Not reproducible on OSX 10.12.3;
- Reproducible only when full-screened is minimized; not reproducible when Editor window is rendered or when it's rendered not in full-screen mode;
- Reproducible only when Service tab is displayed in minimized Editor window.