This is a part of RunUO that allows the editing of map data.
The unfreeze the map option allows you to remove or alter the objects that make up the map, this is the data stored in the MUL files, my only word of warning would be to un-freeze small sections of the map until you get the hang of it 1st.
You can un-freeze a small section of the map and use a tool like Pandoras Box to add extra parts (more commonly called statics), once added you then re-freeze and those extra bits get added to the MUL files.
Once this is done you patch those MUL files to your server and players, this allows the players to have the same files being used by the server, a common cause of confusion is generally players bumping into inv'd items which they can't see which usually means there copy of the clients MUL files differ from the ones your server uses... so in essence theres a mis-match of what the client knows and what the server sees.
The DataPath.cs file (if it's still used) will need to be configured first to allow the server to know which MUL files to use, better to have all the required MUL files in a safe directory that the server uses, seperate to your game client's files before you start to play with this option tho.
Once you've added an item to your map and re-froze it into the MUL's, patch and restart everything, if you were successful you'll see the new object in the radar map viewer thingy in the game.
If it's not there it may mean it's actually there (to the server) but you can't see it (thats why the players require the patch) and you keep bumping off something you can't see.
Thats how i remember it from the last time i did map work but if you try a search on the forums you'll find alot about this subject.
Good luck
