On Linux, Mouse input is not capture in Skeletal mesh editor -> Section Selection right click menu

Attempting to interact with the pop up menu that appears when right clicking in Skeletal Editor -> Section Selection causes the pop up menu to be closed instead.

Regression:
No - same behavior occurs in 4.17.2 (CL 3658906)

1. Open UE4 Editor (third person template)
2. Open SK_Mannequin skeletal asset
3. Click Section Selection in the upper left toolbar
4. Right click the mannequin in the viewport
5. Left click in the pop up menu

Result:
The left click registers in the viewport rather than the menu. This causes the menu to close as though the click was outside the window.

Expected:
Menu registers and responds to the click