in a theatre they can pre-plan everything.

This isnt designed as an 'online' type compositing tool - something like Harry or flame or henry.
Broadcast people are used to those things.

And even these things didnt work fully in real-time last time i checked.

Im just trying to do simple compositing and dissolving. that has to work in real-time.

I cant do chroma keying either - properly - because those broadcast people have devised some kick ass keyers - that i cant possibly compete with.
There is no way i can make it idiot proof - keying is really problematic. and there are alsorts of tools available in the non-real- time world to make this acceptable.