Antialiasing makes Gem Editor transparent (windows)?

[Skull Kid]

This is what it looks like with antialiasing turned off (first image) then turned on (second image).

EDIT: I tried installing Windows 8 Release Preview (removed now, now only using Windows 7) and then the graphics bug in the Gem Editor was gone! Does this have something to do with DirectX or such? I run Windows 7 Ultimate 64-bit with a NVIDIA GeForce 470 GTX and a Intel Core i7 processor @950 with 3.07 GHz.