Reproduction steps(GIF attached):
1. Open attached project.
2. Open "Test" scene.
3. Go to "Edit > Project Settings > Player" and set graphics API to OpenGLCore.
4. Select "Earth" game object in the hierarchy.
5. Expand material properties.
6. Click the eyedropper from the material's Atmosphere Color property.
7. Refocus Editor window(ALT + TAB).
8. Editor crashes on:
--
0x000000014156885F (Unity) ActivateGraphicsContextGL
0x0000000141568A68 (Unity) ActivateGraphicsContext
0x00000001401D0AC5 (Unity) SetupGraphicsContextFromWindow
0x000000014157979E (Unity) WindowGLES::Reshape
0x00000001415637B7 (Unity) GfxDeviceWorker::RunCommand
0x0000000141564D2F (Unity) GfxDeviceWorker::Run
0x000000014155C8FD (Unity) GfxDeviceWorker::RunGfxDeviceWorker
0x00000001405C8518 (Unity) Thread::RunThreadWrapper
0x00007FF81CE48102 (KERNEL32) BaseThreadInitThunk
0x00007FF81F4BC5B4 (ntdll) RtlUserThreadStart
--

Reproduced with:
* 5.4.0b21, 5.5.0a1
* Windows 10

Not reproducible with:
* 5.3.5p4

Related to 801975:
* Reproduced in the same way, but with DirectX instead of OpenGL.
* Console is flooded with "SUCCEEDED(hr)" errors instead of crash.