In X3 32-bit I can't seem to find it in the shortcut menu. In X1 I bound it to the Alt-B key. 

Not sure if the function has a pre-defined binding but it is available in the keyboard shortcuts Track View area and Alt+B appears to be free.

Ah I see it now.
Two weird things here:
+ The first setting, "Global..." isn't actually ALL the functions...so trying to search for "bounce" didn't get any hits in the filter. I had to select the right category first. Weird, I thought there was an "all" list to search from.
+ Turns out the keybinding was already there and persistent from X1, but it didn't show up as bound until I had the Track View list of commands up. It appeared like it was open and available under any other filter. Which, I think, is less than desirable.

Yes, the Global area does not contain all functions. The Global area are functions which may be called regardless of the current view. With the exception of Global bindings, key sequences may call different functions depending on the view, so it is necessary to scan the proper area.

I have to agree with wicked ... "Global" is pretty much universally, dare I say, understood to mean "all." If it doesn't in Sonar, then please, Bakers, either redefine it to mean "all", or if it's simpler, add an "All" category. Having to do several searches if you're not sure where something is needlessly tedious. Especially for folks like me who are still working up the learning curve.