https://learn.microsoft.com/en-us/windows/win32/api/d3d9helper/nf-d3d9helper-idirect3ddevice9-testcooperativelevel
IDirect3DDevice9::TestCooperativeLevel (d3d9helper.h) - Win32 apps | Microsoft Learn
The IDirect3DDevice9::TestCooperativeLevel method (d3d9helper.h) reports the current cooperative-level status of the Direct3D device for a windowed or...
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