Looks good
Are all this code in C script ? what library GUI ?
It is fast enought ?

Does it allows to run the example quikcly even if not in real time ?

what lacks is some mini window showing a fast real time view of the selected 3D model in some panel or another window.
Or perhaps when you select a 3D model it appears semi visible in the editor before you press "enter" to craete it in the scene ?
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I had anotehr idea for a fast editor :
Coded in some open source 3D engine or non open source in C++ for example to be fast.
Actions names would just be configured in some XML definition file (you could even add new action names or remove in the editor and save the config file).