Can someone with the context f these strings?

"Hover (Key Toggle)"

I know it┤s used when adding gadgets to desktop but I can┤t get an accurate translation.

"Use shaped windows instead of ARGB"

What are shaped windows?

"Enable fast composite effects for overrides/Disable composite effects for overrides"

What are these "Overrides"?

Regards
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SÚrgio Marques