1) create a family with just a few text items in.
2) assign the bullet behaviour to family (speed = 0)
3) on some event, add action
4) Select text family.
5) Double click "set angle of motion"
6) now the "objects with expressions" popup appears.
However, there is no other window present where you can just type in "0".
I.e. you have to select an object, e.g. "system". Then you can only pick say a global variable.
So as a work around, I had to create a global variable called ZERO and another called ONEEIGHTY etc for all the angles I needed in the game.
However, this workaround doesnt work if there are two values, e.g. Move X pixels at angle Y, as it only pops up one "object with expressions" popup, which puts the global var in the angle, and hard codes the number of pixels to move at 1.
I was assuming that there was another window hiding somewhere, but when I do the Aero walk thing (windows-tab) or alt-tab, I cant find any other windows.