Map-zooming gives graphic corruption.

the video is just a loaded map, displaying it's behavior while zooming in/out.
When severe corruption is visible, (zoomed out) it does not respond to drag.

tested on current master, but it's been like this the past year.

https://youtu.be/9vahfAQqNpo

Start by reproducing the map zooming behavior on current master, using the linked video and the reported zoomed-out state where corruption and drag failure occur. Trace the map display and zoom handling to identify the cause; done means zooming no longer corrupts the graphics and dragging remains responsive.

Written by the indexing model from the issue text.