There should be a way to drag a cluster in the list, by opening a rectangle selector with a right click in the mouse.

Also, some bugs and improvements needed:

1.when you select a system (yellow circle) the background is erased.

2.if you zoom out while selecting systems the coords do not zoom, yet you have still the ones you selected but when you want to select a new one it's impossible because it selects a random system (that you cannot de-select btw).

3.A good improvement would be to show the system coords you're selecting, somewhere in the sidebar or in a popup window that you can copy and use as system links (wiht the standard format, the mapgen format and the link format). This way you can "actually" use those lists for something and not only for viewing them in the map (paste in mapgen, send in a msg like links, draw a core format, etc..).  This system coords should appear also when you select a created or a default list.