Quote Originally Posted by tbscope View Post
However, Qt Creator does not need a custom Qt core lib. If this lib is used by Qt Creator, I have no idea why. Maybe Nokia thought Qt Creator could be used without Qt installed? I don't see a reason why.
Because of two reasons. One is that Creator uses a bleeding edge version of Qt. Another is that you can rebuild Qt and it could influence Creator.

Quote Originally Posted by tonnot View Post
God ... can anyone talk to the people of Nokia? (Wysota ?)
Hmm??? What do you want me to talk to them about?

Tbscope say:

The question is that QTCreator does not run if I have not a properly QTcore4.dll.
And If I have not this QTCreator build with mingw, I cannot view my own custom widgets plugins !
(I Have mingw compiler, not MSVC )
Really I dont know how to do this.
Qt Creator is like any Qt based application - it needs Qt to run. You can either make it available in the PATH or copy its libraries to the directory where the binary of the application resides. Just like with any other application dependant on some library.

Am I the only QT user that has this problem ?
Probably yes.