Is it possible to pass a variable to a label, essentially the label text itself, on a toolbar?
No, not currently.
So you're saying there's a chance...
There's always a chance. Not in the very near future, though; it's not something we're working on right now but the idea has come up so it might happen one day.
3+ years later... Thoughts?
You can pass variables to be displayed on the Status Bar. Scroll down to the Variables section for a description.
Thanks for this, but not what I'm after.
We haven't forgotten the idea, but it's not about to appear in the next version, no.