Not sure if this is a bug, or maybe a feature that needs to be implemented.
Region Controls dropdown should always show on top. Currently, if there are two regions close to each other (e.g. in the image below), the dropdown displays underneith the second region, leaving it inaccessible until the region is moved.
Z-Index of the region might have something to do with this, but regardless, it would be best to make the dropdown always show on top.
Hope that makes sense.