Not a button, but highlighting the desired notes then right clicking next to them (on the staff) will bring up a pop-up menu wherein you can select Quantize and make the change to duration there (without having to move them around on the staff).
Creating macros in SONAR/CbB would be cool like in MS Word. (I guess that's what CAL is for.) Linking the macro to a new button/tool would be even cooler. Sounds like a feature request... where's my stationery?
Kind regards,
tecknot