The WM_PAINTICON message is sent to a minimized window when the icon is to be painted but only if the application is written for Windows 3.x. A window receives this message only if a class icon is defined for the window; otherwise, WM_PAINT is sent instead.
WM_PAINTICON
This message has no parameters.
An application should return zero if it processes this message.
The DefWindowProc function draws the class icon. For compatibility with Windows 3.x, wParam is TRUE. However, this value has no significance.
DefWindowProc, WM_ICONERASEBKGND, WM_PAINT
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