Qt, by default, mimics the look and feel of the host OS. On Windows and Mac, Qt uses native GUI elements so it's a little unfair to say it doesn't look nice. A

Qt, by default, mimics the look and feel of the host OS. On Windows and Mac, Qt uses native GUI elements so it's a little unfair to say it doesn't look nice. A well laid out Qt program should be indistinguishable from a native application. I'm sure people have very strong opinions on whether native UIs are nice or not! The issue, as you point out, is lack of designer. Both Qt and GTK can be extensively customised, but you need to know what you're doing (in an artistic sense).