I have had to get a new trackball mouse for various reasons I won't go into. The mouse I was using had a lot of function buttons on it, and I had 5 things programmed into it.
 

1. Ctrl-S to Save
2. J and F5, to toggle between the smart tool and scrub tool
3. Square brackets [ ] to toggle between Track View and whatever other view I was using, usually PRV or the Console View.

 
I have come to depend on these being in my mouse hand.
 
Now with this new trackball, I am short one button available to program, as the new one only has 4. Honestly, I can't do without any of those in the mouse hand, without a serious change in my workflow and/or re-training. I'm posting here to get suggestions for a solution. 
 
One idea might be to enable auto-save which renders Ctrl-S less necessary. But also, I'm wondering if there is some sort of toggle option available wherein a single keystroke would either toggle between Track View and PRV/Console, or else one that toggles between Smart Tool and Scrub Tool. Having a single key that acts as a toggle would save me that fifth programmable button.
 
This is the trackball I'll be using, in case anyone wonders.
 
Ideas?

"You can assign hotkey shortcuts to each button.  You can also perform “Chording” (assigning a hotkey to the combination of two buttons pressed at once)." Looks like you should be able to get 6 total commands including right and left click.
 
http://www.kensington.com/us/us/6498/trackballworks-customization-software
 

Yes, exactly so. But of course I need left and right click too, so 6 minus those 2 equals 4!

In case anyone runs across this, I discovered there is an option to assign a keystroke to Show/Hide Multidock that serves this exact purpose.