dwmapi.dll global hook

hello, i don’t know if i’m posting on the right place, but i’m in doubt about something. When i try to open a game, Comodo tells me that “dwmapi.dll” is trying to set a global hook. I don’t know what a global hook is, and i’ve done some research on the internet, aparently i can’t find an explanation. So what is this Global Hook? Is it safe to proceed with it? Thanks a lot.

dwmapi.dll is related to windows desktop composition i.e. the fancy Aero glass desktop theme in Vista and above. As long as the dll is signed by Microsoft I would gather this is a safe global hook for some video mode the game is trying to set up.