Steps to replicate the issue (include links if applicable):

• create an STV election with 2 candidates and 1 seat
• wait for it to start
• go vote
• drag candidate A to the right side (1/1)
• try to drag candidate B to the right side

What happens?:

• the mouse pointer remains a normal mouse pointer, even though attempts to drop it there will fail (do nothing) because the maximum # of candidates you can vote for is 1, due to there only being 1 seat.

What should have happened instead?:

• the mouse pointer should become the CSS not-allowed icon. this is consistent with the icon that is given when dragging a candidate into an area that's not allowed. so it would be good to get both of these not allowed behaviors using the same icon

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):