I'd have some suggestions to make animating a little more handy, don't knof if someone already suggested it.
-bigger canvas size (so that if a stickfigure gets outside of it, you can move with the scrollbars left/right/up/down to it) or a zooming feature for the whole canvas.
It sometimes happen to me that I have some figures outside the stage and press ctrl+a and then scale everything bigger(for example). that way I kinda "loose" my figures outside the stage. I have a lot of figures in the file most of the time, scrolling through with the mousewheel is not a good solution,since I don't know which figure i am currently selecting with it. selecting one part of attached segments doesnt help since i cant select the whole figure then, to get it back by for example using "move to center"
-seeing the stickfigure name when selected (maybe somewhere on the bottom? or in a sort of list of figures?) would be helpful for when a figure is outside of the canvas, and also when using lots of little sticks, especially when replacing them in every frame (I do that when I need to edit something in after I made the animation)
-whole figure is marked when selecting the center joint of a combined figure (when a figure is very big and parts get out of the canvas, but are attached to the figure- or when it has alot attached figures and you have backgroundsticks there too. can be confusing to need to select all the right joints in each frame)
-ability to change nodes color-would be helpful for multiple stick use)
-lock nodes on stage (so they cant be selected or moved the time it is locked)
would be helpful when certain sticks should stay on place while moving everything else
-A little display maybe for rotation and length information of the selected segment (would be VERY helpful for tinier movements and to get a segment back to original length. that autosnapping you implemented somehow doesnt work all the time, for example when the segment is much longer)
it maybe would be nice to edit length and rotation directly with numbers (writing in 121° to rotate it from 120 to 121)
-as often said, the polyfill for 3 or more nodes :D also the copy and paste from one frame to another, which I already saw you implementing.
Kind of a preview of one frame, where you see the output without what is around the stage (animating mode:nodes visible, preview mode: no nodes visible, and you cant move something then). the nodes sometimes cover what I need to see. exporting to an image everytime just to see what I have is time intense.
I know that you want to keep pivot simple. those are just some suggestions which could make the usage maybe a bit easier for, maybe, experienced pivot users. I find pivot a really great program, and I like the idea of it. adding stuff like the above would simplify the animating itself by reducing the time expenses.
for example:
I need half an hour for making a decent background, but only because I need to "fill" everything with segments when I want to have a color in it. I want to be creative in this program, but having to "fill" stuff like this, breaks it down enormously.. Iyes, I could use sprites, gut I want to move stuff in my backgrounds.)
Having, lets say, 50 frames done and editing a new figure in takes me about 5 to 8 times longer just because I have to reposition the figure again all the time. (but as I said, it seems you already make copypaste. : D )
I need to search for the right stick too long (in my opinion) when it happened to be outside the canvas. it happens to me when accidently resizing all figures. (once deselected- not intentionally- they're kind of lost outside.)
Selecting all joints of one stick with attached segments is in my opinion just annoying when i want to resize the whole figure.
When I have border sticks (for decoration at the borders of the stage for example) which I dont want to resize, I need to deselect them everytime / only select those I want to resize. its no big deal, until there are more than ~30 sticks in the stage (counting in the attached segments too, because you have to select all of them separately)
I hope I could give you some good ideas with this. And I hope you don't think too complicated about them, those Ideas are just suggestions to make animating in pivot more attractive and handy.