Layer display toggle button has no layer identifier.

[cityremade]

At the moment for analytics needs we cannot tell which layer is the parent of each display toggle without an acrobatic selector.

To add a data attribute to hold layer key apart from only data-id=display-toggle for each element.

It would make it clear which layer was toggled.

I don't mind adding it to .header. Way better than 3rd parent.

[dbauszus-glx]

Yeah. The assignment of layer-drawer as data-id is bad. Let me fix this.