Hah yeah looks like your right, instead of using "Set Y" and using impulse to push it upwards, it works fine! However, and I'm guessing this is just a physics limtiation, but upon adding another object (and a few "ForEach" actions), it seems that all objects will copy the last objects collisions. Capx
Out of curiosity, howcome the physics behaviour allows you to disable collision from individual objects, whilst the general collision for sprites only allows ALL collisions to be enabled or disabled?
I've come across 2 different scenarios where fine control over collision would be really useful, one involving regular collisions, and one for physics collision.
1. Jump thru + physics. My platformer game has objects scattered around with physics behaviour that can be thrown about. The game is working very well (fully aware we should never combine physics+platformer behaviour :P), but if there is a Jumpthru platform (which would have immovable physics behaviour on it), the object wouldn't be able to go through the platform as it's travelling up. Having control over the collisions would allow me to disable collisions with jumpthrus whilst the object is travelling upwards, and enable them when travelling downwards!
2. Portal style game. One major important thing would be disabling collisions with walls/floors as one is overlapping a portal, but not disabling all collisions as there needs to be a small amount of collision on the edges of the portals (Otherwise when you overlap a portal, you'll just fall). I ended up making a platformer engine with JUST physics to try and make this miniature portal game, and the collisions were crazy and seemed very unpredictable. I should have kept that capx but gave up and didn't save it :P