kind king knight wrote: I think you miss all the points: Trolltech provides a GPL version of the current Qt (4.x) for Windows. And regarding the audio capabilities of Qt, well, you couldn't care less about it when you are developing VSTs, etc. plugins, since audio is provided by the host through the process callback. Robert, I'm in the same track for the clam project http://clam.iua.upf.edu/ Currently you can automatically build a VST dll from a clam network definition. Now we want to add Qt interfaces as we do with standalone prototypes: http://iua-share.upf.es/wikis/clam/index.php/Network_Editor_tutorial We have not started doing experiments yet. However, it seems that it is possible, at least using an additional window http://lists.trolltech.com/qt-interest/2006-01/msg00332.html#msg00332 Probably the extra window is needed because that Qt (GPL Win version) doesn't give interface to adopt a (VST) window. On the other hand you can find VST plugins based on FLTK, like ZynAddSubFx, I guess FLTK can adopt windows. Please report any success on that, I'll also do. Best, Pau -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.