Steps to reproduce:
1) Download attached project and open in Unity
2) In the Project window, go to Assets >> Scenes folder
Note there should be default "SampleScene" scene
3) Select any area in this window
4) Click Ctrl+LShift+B to open Build settings
Note: Build Settings window will not open
Check the attached video of reproduction

Expected result: Ctrl+LShift+B shortcut should open Build Settings window
Actual result: Shortcut doesn't work

Reproduced with:
2018.3.0a6, 2018.3.0a7

Not reproduced with:
2018.2.2f1, 2018.3.0a5

Regression since:
2018.3.0a6

Not reproduced using MacOS machine
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Fixed in:
2018.3.0a9