Hi again Ven, I'm back home now. I have not been able to reproduce this error in my Windows 7 and Windows 10 machines. Looking online there doesn't seem to be any known issue with Dear ImGui related to this kind of distortion.
My best advice here would be this: try to ensure that you have the latest drivers for your GPU (Intel HD Graphics 4000). If you have an old driver there might be some problem that is corrected now.