Stop 0x1E Switching Between System Menus in Application Window

SYMPTOMS

When a child window of the main window is created in a separate UI thread and the child window has the WS_SYSMENU style, when you switch to the child window's system menu by pressing the right arrow, the system stops responding and, eventually, after switching between other applications, the following blue screen STOP message may occur:

For example, if an MDI child window is running on a separate thread and you select a menu item, such as the File menu, and then press the right arrow key, the frame or application's system menu will appear (that is, where you move, size, minimize, maximize, and so on). If you press the right arrow key again, the child window's system menu will appear. After you arrow down, the menu items are not highlighted as expected. When you switch (press ALT+TAB) to another application, the system menu remains on top and does not redraw properly.