In Blocks Editor - With an already defined procedure and its call within a WHEN BUTTON 1 CLICK:-
If an attempt is made to rename the procedure by repeated quick backspace deleting of the current name, then App Inventor suddenly opens in Designer View with a different previously saved App.
There doesn't appear to be any other detrimental effects - Returning to the original App has the procedure with its name partly deleted.
PS: I'm on the nursery slopes with App Inventor and this problem occurred using Windows 7.
The problem with that (according to me) is the Network issue
whenever there is No internet access the changes which are made are not saved
we see the changes done but they are actually not getting saved