I'm not on github, so I hope you don't mind me giving some feedback on thea here instead.
Being able to change the colour bar values is a great feature, but it needs a little more work.
1. The three options should be a selector and not tick boxes, as only one option can be used at a time. Put them on top, otherwise all you see are the boxes where the values are and it takes a while to understand why you can't edit them.
2. The "apply to all slices" should come up with a warning if the dimension it is applying over is large. I ended up having to force quit because it took too long to go through all my slices.
3. I would like to be able to manually set my contours to values like -0.0005. Currently, I am only allowed to put in up to two decimal points.
Great product, I look forward to seeing it develop!
Leon