Add variables support for publish panel

[mliubimov]

Now it seems like the publish panel does not support variables. Therefore, it is impossible to send a value that was modified by a slider, for example.
I think it is possible to add something with this syntax:
{ "field": $variable }
I think this could help to create more advanced logic for the UI.

[Onicc]

I have the same problem; I don’t even know what the slider is for.