Qt is available under LGPL while Gtk is ONLY available under LGPL. So there is NO difference if you use the LGPL libraries. However Qt has the benefit of also being available under a commercial license, while Gtk is not. The advantage of a commercial license is that you can change the Qt library and do not have to publish your changes to Qt.
see http://www.gtk.org/ and http://qt.nokia.com/products/licensing
Hmm, I see.. But Gtk+2 is fully LGPL then in other hand QT as Leledumbo said, "Hmm... I don't know if QT is now LGPL, if that's so, then yes you should be allowed to.". In my conclusion => I can build commercial app using it..
But the real fact, I saw QT providing Commercial License to be used in commercial purpose, and then they provide OpenSource Edition too, which release as LGPL'ed.. Again, in my conclusion => If I want to build commercial app then I must buy the commercial edition, Right?
Disadvantages: licensing restrictions (LGPL); less KDE than Gnome desktops installed (although this does not preclude having both Qt and GTK+ libraries on the same machine); Qt widget set incomplete in Lazarus.
This issue of licensing restrictions does not apply since a long time. Plus, I'd say LCL-Qt is actually better then LCL-Gtk2, so this item does not apply either.
For me the only disadvantage of LCL-Qt is requiring libQt4Pas.so to be installed and potential versioning problems with that library (for example a Linux distro might ship an older version then your app requires).
Thank you for the info, Sir..
2). I saw QT Release new version (QT 4.7.3), so I download it), I also download FPC QT4 Binding (The latest binary binding library)=> QT4Pas5.dll v2.4. But I saw in the Binary Binding package QT4.pas (an unit for QT4 Binding) then I take look into Lazarus I saw the same Unit (QT4.pas and it refers to QT45.pas). What should I do if I want to use QT 4.7.3 + FPC QT4Binding (The latest)? Should I use QT4.pas which shipped inside Lazarus or I must replace it using the new which shipped with FPC QT4 Binding package?
I would use qt4.pas shipped inside Lazarus if you are developing using the LCL, because that is what is tested by everyone. Qt is backwards compatible, so even if you download a new version of Qt, it should still run your LCL-Qt app which has headers for an older version of Qt.
Ok, I'll do your suggestion.. Thank you so much, Mr. Felipe..
Regards,
Takeda.