[Feature] - Disable / enable each individual onion skin

[feeef]

The ability to disable the onion skin on a specific frame while onion skin is on.

I have an animation with 10 frames. I want my last frame to match the first one. I don't want onion skin to be shown between 1 and 10.

Krita and TVPaint both handle opacity on each individual onion skin. I don't think this is absolutely necessary as long as we can easily switch on and off each individual onion skin.

[aecepoglu]

Duplicating the frames I want to copy off of is a good solution to this.

[MrStevns]

This feature could be simplified. In your case @feeef, implementing this such that the last frame sees the first frame, then there's no need to choose which frames you want to be translucent.

Being able to control which frames you want to skin between, would be cool too though.