My problem with that was that more complex Qt projects tended to have 'smart' dialogs and forms, many of the actual signals, actions, etc defined in the forms. Which is cool and makes it easier to see what's going on, except if you want to swap in another UI (say, because you were porting an UI to WinCE), it turns into a hellish tar pit. So you had a choice of throwing out the sophistication of QDesigner and do coding UIs head-to-code, like Real Men, 1999 style, or battle the bugs of never-quite-in-sync .UI-s. And peppering code with #ifdefs by design in a multiplatform framework is also a bit of a drag in 2010. For me, thus, the question is not how difficult it is, but rather if it is really necessary or not (we could just as well have a QMacApplication and a QWinApplication, but we don't and that's not because it's hard to put an #ifdef around it). Just my 2 cents