Hi fellows I'm developing an app using win32 API(not MFC) and I would like to insert in my app a control like this(that is rounded with a black line). It was extracted fron Visual Studio 6. How can I create it:

...? Firstly, you'll have to be more specific. A window that docks, a tabbed pane, just a smaller document sub-window, all of those?

The other thing is that there isn't one you can just dump into any program. Firstly, win32 doesn't really have any of the pretty sorts of windows you see lying around in most windows applications. It is possible to create a new child window class and manually overwrite its repaint/input functions to produce a window of the sort you desire, but that's a rather lot of work.

.Net and MFC have many of the common sorts of windows you see, and you may want to look into one of those (I'd suggest .Net), although at least when MFC was around, microsoft was quick to point out that they don't use MFC for most of the stuff that they sell. I'd go out on a limb and guess that MSVC was included there.

I've never used it myself, but if you're just looking to quickly embed a bunch of sharp-looking window controls, wxWidgets has received some good reviews (http://www.wxwidgets.org/) so you might want to check it out and see what's available.

Slinky730 is right, however there is other application that has done this. This is a good start, however done in WTL and kind of advanced.
One of the samples has a similiar docking window style as seen in the above picture.