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.
Repro
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
I was able to recreate the issue on our end following your repro steps and have submitted the following Bug Report: JIRA [UE-25681]. When this issue has been resolved for a future release of the engine, we will notify you with an update to this post.
Thanks for pointing this out. I have closed JIRA [UE-25681] as a duplicate, after testing to make sure that it indeed resolves the issue reported here.