Hmmm that's a bit trickier but I think it's doable.
Create a variable called "URLis".
Create a system event every tick - choose "Set value" for the action:
Set the value of URLis to the appropriate Browser object expression (i.e domain, path or hash - hash seems like a good bet here).
From here you can call events with the conditional of the URLis value, such as displaying buttons.
That's my best bet; all of this is from memory so I'm sorry if it's off - Let me know how you get on!