** Should remember which background imagery layer you had previously selected
** Background imagery layers should match those of p1
** Dialog for adding custom imagery url
-** Dragging a node under the toolbox and then mouseuping doesn't get passed to the map, so you end up with a node "stuck" to the pointer
** onDataComplete fires the first time a map call has returned - but multiple calls might have been made, so really we should count them and only reset dataWorking when it's back to 0 again
* Mouse wheel zooming
* CSS editing