Here goes part of the patch notes related to the Game Master mode
Game v3.0.150.188Game Master mode- Updated music tab. Added new music and fixed several playback issues
- Added support for multi-region levels in GM mode:
-- If level contains several region triggers buttons will appear on minimap allowing to switch between them
- You can now drag items with or without snapping to terrain (by pressing the Caps Lock button)
- Fixed inconsistency when spawning and dragging an existing item
- Fix for characters sometimes not being assigned to anyone when a player disconnects from a GM session
- Fixed error 300 and error 302 issues and related crash when trying to load zones that had a global entity removed
- Fixed not being able to see custom stats tab when playing with controller
- Fixed a crash related to NPCs joining dialog
- Fixed a crash related to duplicate characters not being cleared correctly
- Fixed a crash when dragging certain items to inventory
- Fixed AI type panel and Alignment context menu not closing when GM changes character
- Fixed an issue causing the encounter panel to display characters in the wrong order if there is a global character
- GMs are now able to change the layout of add- ons for savegames (active sessions), as well as add new add- ons for already ongoing sessions
- Fixed player character being teleported incorrectly when GM takes item that player was sitting or lying on
- Users no longer lose Action Points when the GM manages their items during combat
- Fixed exported characters not having the correct skills memorized
- Fixed item use state being broken after GM has moved it to his inventory and back into the world
- Fixed peace mode after saving and loading
- Fixed cancel button in Level Templates search field
- Fixed swapping around items not being synced correctly to clients
- Fixed being able to load a pin with a deleted scene
- Fixed Character Sheet background after managing a Character
- Fixed incorrect tier of items being generated for creatures
- Fixed GM not being able to do a GM roll during combat when possessing a character
Mods- Fixed an issue with downloading add-ons from the host when entering a multiplayer game
- Fixed a possible global entity duplication issue when downloading an add-on into an existing campaign
- New items in mods now get added to an existing savegame if the savegame already contained the mod and the mod is of a newer version than the version in the savegame
- Mods now get loaded after the lobby screen in order to avoid players having to download mods just to enter the lobby (for Campaign and Game Master)
- Fixed mod downloading and uploading errors due to incorrect renaming of mod files
- Players can now load add-ons when loading a savegame:
-- There is "Gear" icon appears when selecting a savegame of GM session allowing to change mods added to the game.
More info
here 
