I can't do it ....
Even I put the .h file at D:/Qt/qt/plugins/designer/
and I write at .pro file :
INCLUDEPATH += D:/Qt/qt/plugins/designer/
nothing .....
error : No such file or directory

What more have I to include at .pro file ?
I'm searching into QT Help something about 'How to use your own customwidgets plugins' but ....
Help, please . Any good link ?