Hello!
I'm late to replying here; sorry about that! I've been pretty busy the past few weeks. As the recent news post mentioned, I plan to recreate MasterPlan from scratch, and I think I might get rid of the Line Task entirely in favor of easier linking between Tasks / Cards. You mention using the Line tool to create graphs, so I'd like to know how you were using it so I can cover that use-case if possible, as well, and make it easier to do so.