I’ve requested this before but I think it got lost in the shuffle. I think it would be nice if you could right click a parameter and have an option saying “pop parameter to parent group layer”. If the current layer is a sublayer of a group, then a copy of the parameter appears in that group layer. This would allow users to quickly manipulate parameters that are especially important to them without having to navigate deep within group layers.
I have a few more suggestions to make this even more robust.
It should be possible to rename parameters. For example, if I pop two color parameters, I’ll want to distinguish them somehow, maybe as “outline color” and “fill color”.
It should be possible to link parameters that have been popped in this way. I’m not sure how this would mesh or clash with either the ValueBase Nodes menu or the Sets panel.
Finally, it would be nice to hide parameters. (I think this would be a great feature even without the “pop parameter to parent group layer” feature.) Many layers feature parameters that the user no longer wishes to work with. The user could select one or more parameters, right click, and then select “hide parameter(s)”, which would cause the parameters to be lumped together at the bottom of the parameters panel under an expandable “Hidden parameters” list.
I’m not sure how ambitious these changes would be, but I think they’d make Synfig outstanding for large projects that have many parameters with complex linkages.