Edit: this problem has not been fixed in ver. 1.141


The key sequence (F1/E) does not function with maps created previous to 1.14.
Activity description: Load a 1.1331 map or earlier with entities included.
Run test mode then invoke the afore mentioned key sequence with the intent to move or rotate a selected entity.
Result: The entity will change color indicating it is ready to be selected, press the LMB with the cursor on the entity. The moment the LMB is pressed Game Guru will freeze, leaving the mouse or any other activity inoperative.
For all intents, your session will appear frozen and will need task manager to abort the session.

Appearances can be deceiving... Wait for 30 seconds or perhaps longer, the screen will partially clear and the "Resuming from previous session" will appear and the editor will eventually reinstate its self. Unfortunately, appearances are deceiving because the editor is now nonfunctional, you cannot select or add entities to the map.
At this point if you send the editor (using the "_"on the top bar) to the task bar and then select the task bar icon to open the screen back into view the editor is now fully functional ... go figure.
This nonsense has no impact on maps created in 1.14.
I can repeat this whole thing time after time.