Changed 'Lines' to 'Line width', for clarity.
Added fix for extra spacing in dropdown labels.
Distinguish between the currently-used line width key and the one the user chose.
Added graph.edgeLabelLegend property to store legend text for edge labels.
Display the edge label legend text.
Removed incorrect comment.
Minor tweaks to edge label legend style.
Fixed connection dropdown hiding when trying to move cursor over it.

(there was a 2px gap where the cursor hit the splitter instead of the dropdown elements)
Fixed adding/editing connections.
Added the ability to remove connections.
Tweaks to the edit/remove connection buttons.