13.2.2 Rendering Formats Before Termination

When an application is destroyed, it is no longer capable of rendering data
it has copied to the clipboard. Accordingly, when the application that owns
the clipboard is being destroyed, Windows sends that application a special
message, WM_RENDERALLFORMATS. Upon receiving a WM_RENDERALLFORMATS message, an application should follow
the steps described in Section 13.2.1, “Rendering Data on Request,” for
all formats that the application is capable of generating.