Okay I see what you mean, as far as I can tell that's a problem with the implementation of GTK on Windows. Hopefully the new version of GTK that's in the works fixes that.
However, what I really need to know is, and please be as specific as possible:
1) Does the error only stay for a split second?
2) Again, when you want to select tiles in the
level display, does the rectangle draw fast, always staying near your mouse cursor, or does it lag behind, as if the framerate is very low?
3) A bit like 1): When the window is maximized and these "multiple windows" show when you scroll in the
tileset display, do they pretty much instantly disappear, without you, yourself doing anything? As in, do you have to click or drag or whatever in the
level display, or does it fix itself in a split second?
Sorry for being difficult, again, but there is a bunch of different causes here that have a similar end result, for example, if the level is laggy and slowly updates when you edit it, then that's one bug (a pretty annoying one I thought I took care of).
And thanks a lot again for the feedback! Hopefully I can get back to adding some new features once these problems are taken care of