This happens every single time I try to change a variable, for example change the tiling of a TextureCoordinate. I double click in the UTiling to select the number, and my cursor goes all the way to the top left of my first screen, clicks the ‘U’ (Unreal Logo) and opens a little drop down menu. Which is pretty annoying since it stops my work.
This never happened before 4.5.1
Please let me know if you need more clarification and I will take some screen shots.
I have found this this occurs with slider boxes (such as the tiling of a TextureCoordinate node). It is a bug and I have reported it to our internal tracking system (UE-4676) for further investigation.