Editor windows do not lose focus when minimized on Linux

Using Ubuntu 15.04, editor windows do not layer correctly when minimized. Control remains with the minimized window.

Ex.
After minimizing a blueprint window, right clicking will still act as though the blueprint is still open. Creating a "Print String" node in this state will add the node to the blueprint even though the blueprint is minimized.

1. Open UE4Editor (any project)
2. Create new Blueprint and maximize the window
3. Minimize the blueprint window to return to main editor window
4. Right click in the main editor window

Result:
The blueprint context menu will open as though the blueprint window was still open.

Expected:
Window mouse control is removed after minimizing the window.