Problem with drawing tool

I just start using toon boom studio for 4 days in Win 8.
Please check my problem with drawing tool (attached here) when I try to draw rectangle and ellipse.
I change workplace many many times and it gone well, but I don’t really know how it works.
Please give me some advise to fix that. Thanks

It looks like the video card issue. Are you using surface pro or any intel (or low model of ATI) card?
Try changing the renderer type from Preferences>Display from OpenGL to Direct 3D or vice versa depending on your current setting. And the restart Toon Boom Studio to apply changes. If it still happens, try updating the video card driver to latest and try again.