Would it be possible to have one control (SetterBar) having access to multiple variables? For example, if I wanted to control variables a and b, could I have one button set (a=1 and b=0) and another button set (a=0 and b=2)?
It is probably best to use a list for this purpose.
SetterBar[Dynamic[x], {{1, 2}, {3, 4}, {5, 6}}] Dynamic[First[x]] Dynamic[Last[x]]
In any case, you could make this work with Button if you wanted to, but using a list would be easier.