1. set the default configuration to a gaussian distribution instead of a constant 49/100.

Done, thank you for the tip :)

2. autocomplete feature : set one bar, then shift+click an other bar completes the inbetween bars with a linear interpolation

Right now you can press Shift key and drag over the bars and they will follow your cursor. This is not auto-completion, but at least something.

3. add a space between the upper button and the vertical bar : since there is no gap, it is easy to missclick.

I would like to have more people saying their opinion about this.

4. clicks between bars is accepted : the clickable section should be narrower.

Erm? Why shouldn't we accept clicks between bars? The visual part of the bar is smaller than the bar itself just for the sake of better visibility, but you can click anywhere inside its rectangle.

5. the behavious of the frame 0 (current frame) is strange : the button does nothing and the bar affects all other frames

Fixed, thanks :)

6. save some curve profiles ?

Maybe a nice feature. Need more input from people.

7. making the background of the bar different from the background of the menu might make the interface more readable.

The background is taken from the system theme as "background of item views". I would need a screen shot to see how it looks in your theme.

8. shouldn't the color of the bar be the same as the one given in the qt theme ?

The color of the bar is the same color as the color of the frames in the timeline. So they look pleasant when docked next to each other.

9. the text should be centered (it is slightly on the left)

I need a screenshot :)

2. the solution you provided might be actually better !

4. maybe I wasn't clear : I can click in the non-blue part of the rectagle. Maybe that is a personal thing but I would prefer to have a gap where some potentially ambiguous click (human precision on tablet or mouse) are ignored.

8. maybe this is personal, but I would prefer all the sliders to be colored the same... As a user I don't dock the onion skin panel, I set it up once, and close it until I want to show 1 frame instead of 3 or things like that... but that's not very important

9. screenshot (also not very important)