A. Components to construct applications that have GUI.
B. Graphical programming environment (usually called IDE).
The Qt (originally Trolltech Qt, then Nokia's Qt) belongs to the first group. It certainly is not the only one. Apple has had their own, UNIX side has Motif (which is C). The thing with application GUI is that it is closely knit to the windowing system, which in turn has close ties to the OS. Apple and MS do provide components to encourage "uniform look and feel".
(In ideal world a single system setting in every OS would enable Emacs (or vi) keybindings in every application and every part of GUI.)
Are you looking for a Rapid Application Development tool that lets you create a program by visually designing the UI? Delphi/C++Builder by Embarcadero.