ScrollBar class captures the mouse and doesn't release it

I'm attaching a Testcase.
Basically it creates an Overlapped window which contains a ScrollBar control class child.
To reproduce the bug:
1)Launch the .exe
2)Left click on the scroll bar region
3)Mouse gets captured
4)Try to move the window. It won't move
5)Try to click outside the window(i.e, pushing the "Start" menu button). It won't work neither.
6)The only way that seems to release the mouse is by:
----Right clicking in any place of the screen(not just in the Window area).
----Pressing CTRL
----Pressing Alt