How to implement dialog boxes like in Paint.NET?

Question

Mobile development

I want to make the same dialog boxes as in the latest (4.0.3) version of Paint.NET at the moment, but I can't find how to do it correctly. What exactly interests me - I can't figure out how to make the area where the "OK", "Cancel" buttons are located. In the screenshot, I highlighted this place:

I also note that if you click on this area with the LMB and do not release, you can move the window in the same way as when dragging the window by the title bar.
Interested in the implementation on WPF, but I will consider all available options.
PS: Perhaps the implementation of such a window will be simple, but I did not find how to do it correctly.

Answer 1

They implemented this effect by calling the winapi function DwmExtendFrameIntoClientArea - msdn.microsoft.com/ru-ru/library/windows/desktop/a... .

Answer 2

You were right about DwmExtendFrameIntoClientArea. In .NET 4.0-4.5, it has a wrapper in the form of the WindowChrome class