Object's part opacity

Hello. My English is not well, but i hope someone will understand me.
I have two backgrounds: “Night” and “Light”.
In game i want to see “Light” thru “Night” in area of smaller object (for example “shape painter” or another sprite).
In two words: i want to make “flash light effect”.

Ooooh… Will be difficult as GDevelop doesn’t have any masking capabilities (though I agrre that it would be cool to have).

So if there isn’t built-in feartures in GDevelop for this, maybe it is possible to make “flash light effect” with javascript code?

Probably yes. HTML5 AFAIK has masking capabilities. Dunno how hard it’d be to do it though.