is there any way to call / start Qtwidget from win32 application ?

[umen]

you mean inner process communication between the process ?

[stampede]

Yes, just open the second app as separate process and write/read to/from it - how to do that is up to you. If you need only to start the Qt-webkit window and get a single string when it's finished, I'd probably use simple stdin/out communication (I mean output this string with std::cout or printf, and catch it in your main app). You can use win32 window messages with Qt widgets as well, so use them if you prefer communicating this way. Or use sockets. Or files...
If porting the app to Qt is not an option, I'd prefer to do this like that, because I agree with high_flyer's previous post.