Add ability to pre-filter application variable list for involvement with selected step only

In general, if you have to deal with a lot of variables, managing them with the current set of functions is very inefficient.

What could maybe help would be a function that would allow you to only display variables relevant for the currently selected step.

If the step filter is active, however, it should still be possible to search the pre-filtered list.

Or maybe add a variables button to the step menu similar to what is already existing on the application menu…