Toggle fat bits mode about decker

[JohnEarnest]

The above commit completes the requested addition.

[JohnEarnest]

I'm not really sure what the benefit is to this over the current method of exiting FatBits via the keyboard- pressing escape. Can you clarify?

[gingerbeardman]

Coming from HyperCard (as I'm assuming a high percentage of users will be) it's usual to keep your finger on the modifier keys and use presses of the command key to zoom in and out whilst drawing pixel graphics.

So it's both quicker to only have to use the one key to enter and exit fat bits, and it is familiar for HyperCard users (I didn't realise you could exit it using escape, I just assumed that you had to use the menu).

[gingerbeardman]

Many thanks, John.