I dont know if this was reported yet, but I will make it short.
Since 4.11 Preview 1 and still in Preview 2, when opening for example the Static Mesh Editor with Ctrl-E, the mouse controls are off and every click in the 3D viewport results in the camera moving upwards (as if ctrl -e was held while having RMB pressed.
- Open FPS example map
- Select a cube static mesh actor and use Ctrl-E to open up Static Mesh Editor
- Press any mouse button in the 3D viewport and you should move the camera upwards (even if the static mesh editor window is closed, this bug is still active)
- End this behaviour by for example clicking into the Content browser window