FR: ability to define prop spawn condition in editor dialog window

As a FREDder I'd like to be able to put a prop in a mission, but define it's spawn condition like an arrival cue (for instance for in-mission jumps or checkpoints). Here's a visualization:

I know there's `prop-create` sexp to spawn props, but they are cumbersome to use when you're designing complex scenes with multiple props and you must fill prop type, x, y, z coordinates and rotation parameters for each.