One of the, hmm, "pleasures" of Mathematica is the appearance of those half-broken UI elements, that are hardcoded in some inappropriate way or another. Another example I just came across is the Image Assistant Toolbar. Here is what it looks like for me:
It turns out that the StyleSheet that's in use does have some effect on how much of that "more..." text fits into its button, but even if I use the default StyleSheet it doesn't fit, on my particular Windows 7 x64 machine. I'm sure there's some Windows machines where this works, but none of mine fall in this class. My guess is that OS settings affect the display of this as well, in possibly mysterious ways. Does anyone know how that toolbar is coded? Is there a notebook that I could edit so this looks the way it's supposed to?
After trying Karsten's suggestion in his answer (which solved the issue in the original image I posted), I checked the other tabs of that bar, and found this:
Overall, font sizes in this interface are a complete and hopeless mess. See this:
and notice the font size for the "other" label at the bottom. Well, I am sure that Karsten may be able to help me ultimately fix this one too, but I am certain that I'll find similar issues with pretty much every single new toolbar that I may discover. One may ask why Mathematica users have to redesign their user interface themselves if they want it to be rendered correctly.