I find this part of the Solid UX really painful 
. I’d be willing to do a call so that you can see me use it and we can discuss what might be good to change and how. I’d love to contribute to this.
There’s little things I’d change like:
- Permanently displaying the icons instead of showing/hiding on hover (just saw you created an issue on this)
- Getting a proper icon set with a coherent design
- Displaying text next to icons to convey meaning (instead of using tooltips)
- Does the whole pane need to be foldable? Do I ever need to do that as a user? When I fold the pane, the control changes position, which means I need to move my pointer to fetch for that control again. Also, what’s the point of having the option to remove the pane with that X? I end up with an empty page.
There’s many more things, some of which I’m not sure how to articulate because I find the design so confusing that I’m not even sure what the intent was or how I’m supposed to use it. That’s why I think that having a call might be better. Let me know if you’d like to arrange that.