How to reproduce:
1. Download attached project file and open Example scene
2. Change Scene View from Shaded to Wireframe

Actual result: Changing the scene view from Shaded to Wireframe leaves an image of the shaded render over the top of the wireframe. As if that frame is stuck, blocking the camera, with the wireframe behind it. Changing the size of the scene window drags that image aside and then removes it. This issue seems only appears while Game and Scene Window are together side by side, changing the layout to default, fixes the issue.

Reproduced with: 2018.1.0b9, 2018.1.0b11, 2018.2.0a4

Workaround: Change layout to Default