Many parts of old GNOME-libs where included into Gtk+ to get rid of the many external libraries GNOME was constantly blamed for. For example the library "GNOME-PrintUI" was merged into Gtk+ at version 2.20. Many other parts are also now included in Gtk+ and are not GNOME-specific any longer.
But back to topic :
I don't understand why this idea such a problem for some people? There was always a constant flow of KDE-developments into Qt. I don't exactly know when but i think that the printing-part of Qt was once developed for KDE and then merged into Qt (Maybe version 2.2 or 3.0?).
Merging parts of KDE into Qt was never a real problem back in the past.