I have been asking this same question from the day Cakewalk got rid of Undo button somewhere in Sonar X1 or even earlier. How hard is it to make Undo button? If you have function already, why not make it a "Button" as it is in Word processors, even in this forum post editor? Every time we have to Undo, we have to go to Edit and make 3 steps to undo. It should be one click operation! I do not have keyboard on my lap when I play Keyboards or piano or guitar or record Vocals. For the vocal- I have to walk away from the mic, open keyboard, make lots of noise. What is the problem with Undo- why is it gone and has not been placed back disregarding of multiple requests? Thank you.

I thought ctrl+z did this already?

CTRL + Z is the Windows default for Undo, and it works perfectly fine in Sonar, all versions.
 
Bob Bone
 

It sounds like the poster of this question doesn't have access to her keyboard at all times.  She has a mouse, though, so it was convenient for her to be able to quickly click the undo button.
 
The toolbars used to be much more customizable, with a lot of options for things like Save, Undo, audiosnap features, etc.  If a person has come to rely on that, it can be bothersome to find that those features have been removed.
 
It might be possible to map a midi note to Undo, I guess, though that doesn't address the issue with guitar or vocals.  If you have a wireless controller, like a Frontier Tranzport or iPod, it should have an undo button.

Wow, I never noticed they got rid of it, since I'm so used to using the hot keys.  Could she possible use the key assignments to assign it to a mouse button?  Assuming she has a multi button mouse.

not sure of your workflow but when you say "for the vocal- I have to walk away from the mic, open keyboard, make lots of noise" it sounds like you expect to be able to use your computer while you are not at your computer.
 
 
surely the different record modes come in handy here, allowing you to do multiple takes while muting previous ones, and then going back in to edit.

Although I've gotten used to Ctrl+Z and a handful of other keyboard shortcuts, I'd still like to have the option of a Control Bar widget that included Undo, Redo and Save.

If your keyboard sends midi you can probably set it up as a control surface. Using a couple of the buttons on the keyboard you could assign them as Undo and Redo.

you could even pick up something like this and have a modified keybinding set mapped to the keys you use most often that you can load up - way smaller than a full keyboard.
http://www.stock4less.com/Wireless-Number-Pad_p_46868.html

On my humungous monitor I have tons of spare room on the control bar. A widget that acts as a container for user-defined button-keystroke mappings might be very cool
I recommend submitting it as an enhancement request.