The second is with the "Button for transition" tool. It seems like the "bottom left" and "top right" positions are swapped. It'd also really help to be able to change the position of these buttons like you can with most other images. It seems like there's only the choice of top/bottom/center and left/right/center. And adding additional buttons will just cause them to appear automatically below the first one, without any option to customize it.
And I've tried to figure this out but it seems like no matter what, these buttons have a border built in to them which cannot be removed. Not sure if this is a bug or what but it's not the sort of thing I'd want on an image button.