Steps to reproduce:
1. Open a new project
2. Enable Frame Debugger and go through some frames
3. Click out of Unity, make it out of focus
4. Without making Unity in focus, move the cursor in the Game View and wait a few seconds
5. Move the cursor out of the Game View and into Frame Debug window or into Hierarchy
6. Observe that some additional information appears in the Frame Debugger

Once Unity is brought into focus simply by clicking the additional info disappears

Expected result: Nothing changes when mouse cursor is moved in the out of focus Unity window
Actual result: Frame debugger shows additional information when mouse cursor is moved in a specific way

Reproduced with: 2017.1.2p3, 2017.2.0p3, 2017.3.0f1, 2018.1.0a7
Not reproduced with: 5.6.4p2, 2017.1.0a6
Regression in 2017.1.0b1