Kenneth
I use Sonar mostly for composing so very rarely do I need more than one track record enabled, but I've left record arm on another track (causing a mess of cleanup later) a couple times.
Is there a way to make record arming a track exclusive so record arming one track disables record arm on another?
No, but you CAN use the "mix module" and add it to your control bar at the top. It gives you a master mute, solo and arm button that will enable or disable your entire project. For example, if you think you may have left a track armed and just want to clear things, just press the Arm button in the mix module and it will shut down any armed tracks you have. Then you can just go to the track you want to work on and arm it. So you're new habit would have to be:
Arm the track you're working on and record.
After you're done so you don't forget or make any mistakes, go to the mix module in control bar and press the master arm so it will shut down all armed tracks and the light will turn out.
Pressing this again will arm ALL tracks. It's just a master disable/enable for armed tracks, but that's the only suggestion I can make to you other than hiding tracks that you don't want recorded over and then showing them all once you're done. Hope this helps.
-Danny