Macro-synteny highlight behavior

[alancleary]

Dragging the highlight bar of a macro-synteny view to a new location loads a new micro-synteny query track, thus initiating a new micro-synteny search. Subsequently, the previous view is destroyed. However, users may be interested in preserving this view, or they may have accidentally dragged the hightlight if they're new to GCV. For these reasons, dragging the macro-synteny highlight should open a dialog that provides the user with the following options:

1. Initiate a micro-synetny search
2. Initiate a micro-synteny search in a new window
3. Cancel