There is no 'Qt Library", it's a collection of many libraries. Do you really use all of them?

That is a good question. Of course I do not use all of them. But can I somehow only bundle the ones I use? I did not not investigate that yet ...

Yes you only have to bundle the ones you use (QTGUI is the big one though and its hard to avoid using), just remember that you can't use the LGPL licensed version of QT on iOS. (or rather, Apple is not allowed to distribute the LGPL libraries through the appstore under their current terms and there is no other sane distribution channel you can use) so you need to buy a commercial/proprietary license for that.

On Android you can atleast use Google Play(Assuming android support is included in the opensource version (i could only see it in the commercial version), not sure if any other appstore has LGPL compatible terms of use but if you link statically it can be quite difficult to comply with the license anyway(and both iOS and Android apps have to be linked statically) if you link statically you only need to include the classes/methods you actually use and the size increase will be negligable.

For distribution on most Linux based operating systems you don't have to bundle QT at all, just list it as a dependency in your .rpm installer and the OS will download and install/update it if its not allready done. (All LSB compliant systems can use .rpm installers even if its not their preferred format)

If you are targeting mobiles you might be far better off using something like wxWidgets (its license only applies for sourcecode releases, you're free to license your binaries in any way you please which avoids the issue of incompatible appstore terms)

If you are targeting mobiles you might be far better off using something like wxWidgets (its license only applies for sourcecode releases, you're free to license your binaries in any way you please which avoids the issue of incompatible appstore terms)

I just google for an android port of wxWidgets. There seems to be nothing functional yet. Same thing with iOS. Or am I missing something?

Hmm yeah, its not really done yet.

Huh, sorry for nitpicking on the original post, but since when Windows 7 is a mobile platform?