Okay, I see what you are going for better here. It’s a text-heavy form of image mark up, and so naturally a text oriented program like Scapple is appealing for the task, over something so detailed that it can treat text as vector graphics. 
I’ll put in a suggestion for locking images (and maybe anything) somehow “to the background”. I don’t feel that goes against the principle of the software, though Keith may not agree, so we’ll see. Thanks for the feedback, all!
I can think of a few… not best suited for driving, however.