WM_RBUTTONUP emitted by error when right-clicking on the title-bar of an application

Contrary to what Windows does, ReactOS emits a WM_RBUTTONUP message when you right-click on the title-bar of an application, and before sending the WM_CONTEXTMENU message, so that, if you internally deal with WM_RBUTTONUP and you don't let afterwards the default Window Procedure dealing with this message, you never get the title-bar context menu, aka. the window system menu.

Windows :
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• Right-click on the title-bar
• WM_NBUTTONDOWN
• WM_CONTEXTMENU

ReactOS :
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• Right-click on the title-bar
• WM_NBUTTONDOWN ?
• WM_RBUTTONUP
  -WM_CONTEXTMENU

Here is a test app programmed by Edijus and Grégory Macario Harbs.