Removing Non-Client area of a window

[Lexis]

How can I remove non-client area of a window (border, title), which belongs to another process (separate application)? I have only HWND of that window, and cutting its DC using SetLayeredWindowAttributes() with LWA_COLORKEY, to get some specific shape, but all non-client area remains as an ugly frame. So I need to remove it somehow.
Note: the window is created by existing application, and I can’t change its code

[Bond]

Try using SetWindowLong to set the window class attributes. For example, to remove the caption (title bar):

DWORD dwStyle = GetWindowLong(hwnd, GWL_STYLE);
dwStyle &= ~WS_CAPTION;
SetWindowLong(hwnd, GWL_STYLE, dwStyle);
SetWindowPos(hwnd, NULL, NULL, NULL, NULL, NULL,
                   SWP_FRAMECHANGED | SWP_NOZORDER | SWP_NOMOVE | SWP_NOSIZE);

[Lexis]

Thanks a lot! Working perfect with:

dwStyle &= ~WS_OVERLAPPEDWINDOW;