Selecting masters is difficult
The method for grabbing a master and dropping it into a screen is too clumsy. If you hesitate at all, you end up opening the master object instead of selecting it, and then you have to figure out what screen you were in.
A better method would be for one click to select the master object and double click to edit it. At the moment, double click opens the master object to the title screen. This could be a right click or even a menu function, as you don't often need to change the name of a master object.