Hi,
I tried the "promotion aproach" described in the "C++ GUI Programming with Qt4" book and it works fine.
Then tried the "plugin approach" and used the IconEditor example.
After building the plugin i get a "libiconeditorplugin.so" file in this path:
Qt Code: 
  1. /usr/local/Trolltech/Qt-4.5.2/plugins/designer
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Now what?
I whant to open QtCreator and have that widget available as any other.
What is the next step?
Thanks