How to Select Multiple Tracks on Mac

I'm using the latest release of Basecamp for Mac and am running OS Yosemite. I can't find a way to select multiple tracks at once for joining. The only option I've discovered that actually works is to drag a selection box around the tracks in question, but if there are multiple tracks crossing each other it's not ideal. I've tried holding the shift key, control key, option key and command key while clicking the tracks I want to join, but none of these keys seem to work. Any suggestions? What could I be doing wrong?