Default key used to instruct the UI to paint an outline behind each edge. An edge outline
can be helpful for users to be able to click/tap on an edge, as it gives them a larger target area. If this is set the outline is by default
transparent, but the color can be overridden either via CSS or with the DEFAULT_KEY_CONNECTOR_OUTLINE_COLOR key.
Default key used to instruct the UI to paint an outline behind each edge. An edge outline can be helpful for users to be able to click/tap on an edge, as it gives them a larger target area. If this is set the outline is by default transparent, but the color can be overridden either via CSS or with the DEFAULT_KEY_CONNECTOR_OUTLINE_COLOR key.