I've been trying to interpolate between timeline and found out some things:
I can't get a read different to 0 from the progress. I managed to get a parameter only if the event is 'on period "...." begin'. How is it used exactly?
A way to get parameters from other periods and timelines would be nice, so I could interpolate between periods (linear, cuadratic, cubic, whatever).
A way to get the current timeline name would be nice.
Some of this ties in with what BonesMovement does. Construct is lacking just some tiny details to allow complex animation / scripting. See http://www.scirra.com/phpBB3/viewtopic.php?f=17&t=3089