Actually, that's what I tried before I asked you. And tried again right now: Nothing changed.
To me it seems that the Tab-Stack part of code receives a wrong Y coordinate for the Window.Top, e. g. the lower edge of the menu or the old position where the tabs used to be before they were set down.
When I switch Colorul Tabs off, one might think that the Tab-Stack still remains on top and the tabs appear strangely cut at their lower edges. I'll attach another screenshot where you can see that.
So this might rather be a problem of Theme Restorer than of your tool.