DerLeiter

First, you need qtcurve-gtk/-qt for uniform look GTK and Qt programs, second, in KDE-based distros all GTK-based programs (wxWidgets uses GTK) looks ugly without "dancing with the tambourine" (installing qtcurve), therefore your example with GNOME is wrong. In any case, I want to offer assistance with porting ApexDC++ on Linux.

I do not understand the reason for which you need precisely native controls on each platform... I use Qt for writing my programs that runs on Linux, Windows and Mac OS X and never had a situation where I needed a native controls on each platform.

Qt 4.6 uses native styles for drawing controls on each operating system such as Mac OS X or Windows.

License specified in source code has a higher priority than the license specified in file LICENSE. So EiskaltDC++ has no problems with licenses. Details

We already have Qt based DC++ client - EiskaltDC++ (http://code.google.com/p/eiskaltdc/). There is ChangeLog