Extracted from the wbc3 wiki:
1. Having too many tile sets causes the editor to be unable to "select" some of the last loaded sets. However, the game still loads the tiles from those sets normally. Although, if you drastically go beyond this tile limit, then the game starts to refuse loading those later tile sets. Admittedly, this is something that any normal player would not encounter. FIXED
2. The editor event "Change to night" will first set the time to "day" before transitioning it to night even if it was already night. Setting such an event to loop will cause the screen to constantly flash day before going dark. All this applies to the "Chang to day" event as well. FIXED
3. The event condition "Move a unit(s) to a square" doesn't actually check for the quantity of units required. FIXED
4. If an event square overlaps with another event square, then only the top one (last placed one) can be triggered by units that cross it. FIXED
5. The item chest panel, caused by clicking on a pre-placed item chest, can't be closed - not even exiting the editor will get rid of it! FIXED
6. After resigning from a game, the editor will then run really, really slowly. This is undone by starting another match and then finishing it normally (victory / defeat). FIXED
7. The editor incorrectly wont allow placement of objects "in front" of an existing object, regardless of whether the grids of the 2 objects have valid positions. This has resulted in me to always build my maps from the bottom and then work up, as the editor correctly uses just the object's grid when it is being placed behind an existing object. FIXED
8. Events following a timer will loose all sense of time if a game was saved and then reloaded. I.E: an event designed to loop once every 3 seconds could end up something like looping once every 2 minutes after a saved game was loaded. FIXED
9. A timed event that requires additional conditions that is triggered, but then has the conditions undone will still continue on. I.E: Imagine a 10 minute timed event that also requires flag 1 on to play. Flag 1 becomes on, starting the timed event, but before the 10 minute timer is up, flag 1 is then turned off, thus meaning the conditions for the event are no longer present - the event, however, still plays on and still activates after the timer is up, despite flag 1 no longer meeting the requirement. FIXED
10. The editor incorrectly claims you can't place an object against the very top and left sides of the map, but you can. FIXED
11. Choosing to move a feature will cause it to create a new grid on the new position, but still leaves its old one behind, still rendering the previous location impassible (if the feature blocked paths, that is). FIXED