uic3 doesn't convert QAction to Q3Action for Q3ToolBar, need doc for that

Q3ToolBar doc says that it only works with Q3Action instead of QAction, but neither uic3 nor qt3to4 tool does the conversion. So it results in the running error which the customer considers as a bug of QAction(or Q3ToolBar). For example, even generally QAction works, QAction::setVisible(false) doesn't work properly here.

feedback from dev team says that it's difficult to add such conversion, and we should not do that, since it's not a simple replacement, given that QMenu doesn't need Q3Action.
So we'd better add more information into Q3ToolBar doc and "Porting from qt3 to qt4" doc, to let the customer aware of this issue.
The best solution is to totally remove Q3MainWindow, and use QMainWindow instead.