I just experimented with some polygons, it’s a nice tool!
One thing I noticed:
I always use a click into the map for closing item labels (pop-ups*), if there is a polygon area behind an item label, the click opens at the same time the polygon label and center the map on it.
It would be nice, if the first click into a polygon area closes current activated labels.
(and on mobile, the first click next to a label should not activate any other items.)
Not as an alternative, more like an additional way to close an item pop-up.
Just by clicking on the name:
Regarding the X-Button, you mean something like that, right?
If you create an X-Button, what do you think about, to make the button static?
I don’t know if static is the right word, but I mean that the button always stays in the upper right corner, even when I scroll down the pop-up.
For example, my info-screen contains a lot of information, if you read till the end you need to scroll all the way up first, to leave the info-screen.
edit: Or maybe a second “X” that is always in the bottom right corner