Ecosystem map lines

[ferrisoxide]

Describe the bug

As reported by @emily-humphreys

When a node in the ecosystem map is double-clicked to highlight itself and its connected nodes, the lines connecting other nodes that are not in focus (i.e. not connected to the selected node) are set to a light grey.

This is intentional, as it makes the selected nodes and their connections (drawn in green) easier to see and deemphasises the nodes the are not selected.

However, once a node has been selected this way it is impossible to return the graph back to the original state. Clicking on another node, or elsewhere on the page, doesn't help as there will always be a set of selected nodes.

The solution might be to allow for an "unselect" the connected nodes if the central node is double-clicked a second time. The expectation would be that double-clicking would remove the green highlight and return the graph to its former state.

As an aside the z-order of lines is unrelated to the highlighted status. As a consequence, when there are large numbers of nodes, the light grey lines can criss-cross the highlighted lines, obscuring their selected status.

Screenshots

Image 1 - when it first loads (dark grey lines)

Image 2 - double click a node

(Lines turn light grey and green connections albeit in this map a little tricky to see)

Image 3 - after you’ve double clicked out of that (see lines stay light grey - would be great if they returned back to dark grey)

[SishaMish]

Related to #960