finding listID at runtime

[Frans Amelink]

I'm trying to initialise a list associated with a popup trigger whenever
this popup trigger is tapped.
So basically in the ctlSelect event of the popup trigger i'll have a call to
my listinit function.
However, I can't seem to get the required listID attribute from the popup
trigger control so that I know which list to initialize.

Any ideas?
Thanks for your help.

Frans Amelink