When claiming chunks it is hard to easily see which chunks you have or haven't claimed, especially with the slowness of the map updates (not to mention the lack of a second monitor for some). I say you should be able to enable some sort of "claim mode" some item would allow you to simply left click to claim, right click to unclaim. To visualize your towns chunks there should be some sort of particle effect, maybe a pillar in the middle of each chunk or some other way to more easily see claim status of chunks. This would allow for easier chunk claiming and comprehension of the system and help to counteract the confusion that may be caused by the fill feature on the map which will show unclaimed chunks within your town as "claimed" on the map.