EGL_EXT_compositor example and behavior


I’m trying to understand the usage of EGL compositor extension.
The easiest way after reading the description of the extension is to see some usage example.
But no luck, I didn’t find any example at all.
So, does anyone have and can please upload some usage sample code?
And my main question regarding the extension:
what is the policy of overlapping windows? Is it just the windows order at attributes list or there’s a blend option between the windows?