[BUG] SetWindowDisplayAffinity and DWM thumbnails

[fixer]

SetWindowDisplayAffinity function enables applications to protect their own onscreen window content from being captured or copied through a specific set of public operating system features and APIs.
And DWM thumbnails are representations of application windows. These are not static snapshots of a window, but are instead dynamic, constant connections between a thumbnail source window and a location on a destination window that receives the live thumbnail rendering. You can see them for example by hovering over an application on the taskbar.
The sad news is SetWindowDisplayAffinity doesn't work for DWM thumbnail windows. Not sure whether it's a bug or a feature, but it's just the way it is.