i learned how to use triggers here: http://howtojcs.zeepost.nl/

I have maked an level where you need to get a door open. To get the door open you need to find 2 clouds and touch them. 1 cloud opens the first tile and the second one the second tile. If you know how it works its very easy.

I dont like trigger crates, why should something open if you kick a crate?

I just use the tileset to get for example a switch, than i make it so that if you touch it somewhere a door opens, I though it even was possible to change the switch at the same time (from on to off for example)