Horizontal/Vertical bar units selector

[plouc]

• [x] adjust ticks count when count is used instead of percentage
• [x] do not display count twice in the tooltip, when count is used
• [x] disable animation
• [x] improve button style
• [ ] put button before the chart, not before the legends?

[SachaG]

I actually thought the animation looked cool :)

[plouc]

It's weird as the bars should remain the same, we just change the display, the proportions are identical.

[plouc]

But if you prefer to keep it, no problem :)

[plouc]

We'll decide later if we keep the toggle before the legends