Map editor broke

This is not the same as the issue found here:

http://brightrockgames.userecho.com/topics/2540-map-creation-frozen/

I am not entirely sure what happened but I suspect the memory bug may have had something to do with this. Effectively, I had just mirrored, saved, and published a map to friends, and the map editor started acting fairly strange. The editor, itself, still worked but the arrow keys no longer functioned. Whenever I tried to place a tile, it would transform all adjacent tiles of the same type to the tile in question. For instance, if I wished to make a dirt tile into a rocky tile, it would transform all dirt tiles, not just the one I had selected. I exited it shortly after, I probably should have taken a screenshot or two but I managed to forget.

A couple of theories:

1 - I was using a map which was 100x100, hence fairly big, and which almost exclusively featured multiple coloured tiles. Hence, it is very likely that this amplified the memory bug.

2 - I had a couple of instances before where the map editor acted strangely, it may be due to mirroring from a corner. A quick setup I once used which caused problems was:

Step 1 - Create a two-player map with equal length/width. I presume that this occurs more on larger maps, so try a 126x126.

Step 2 - Place One dungeon core, such as the green one, in one of the corners. Surround it with fortified walls so that you can see what happens more clearly.

Step 3 - Use the corner mirroring tile. If it works, you should end up with one green dungeon core and two blue dungeon cores, one of which the game does not recognise.

I have no idea if this is the same issue but I suggest that the mirroring tile may be the source of these problems.

Output log:

output_log.txt