Thanks for your help , Okay i am finally able to make it work i uninstalled the whole QTcreator and then re-installed it..then i made the sysroot field empty (This was the reason of showing those two errors) …which was automatically having a path in new qt creator. After doing that QTcreator is stop showing those two errors… this is now solve.
However now inside the QML file if i change the rectangle with gradient it does show the effect on the DESIGNER but when i run this application it does not show the gradient color at all. Secondly whatever position i adjust for rectangle it render on run-time on the different place while on preview the designer works fine. In designer i can format my text to italic but runtime it shows non-italic… Why this is happening??