What I tried to do is pick a standard, very common screen size and keep the Settings window (and the default layouts) within that screen size, as best that I can. I picked 1024x768 because it was very common, and at the time you could be sure that an extremely high percentage of users of the software (and PC users in general) would have a screen at LEAST that large, but usually larger. In case you hadn't noticed, the buttons on each tab are sized in such a way as to keep the entire set of buttons within this screen size. So buttons on one tab may be larger or smaller than buttons on another tab, depending on how many buttons there are.
Now, several years later, who would have thought that screen sizes would actually get smaller? But with the 16:9 ratio becoming more and more common, they did exactly that. At least on some displays, and in the vertical direction.
Before I added the dashboard, this really wasn't much of a concern. But I agree, it might be worth it to investigate keeping the dashboard and tabs in place while allowing the rest of the page to scroll.