TooltipExternalCallback (Charba - J2CL and GWT charts library based on CHART.JS)

```
public interface TooltipExternalCallback
```
External tooltips callback allow you to hook in the tooltip rendering process so that you can render the tooltip in your own custom way.
Generally this is used to create an HTML tooltip instead of an on canvas one.

Author:

Andrea "Stock" Stocchero

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`onExternal(IsChart chart, TooltipModel model)`	External tooltips callback allows you to hook in the tooltip rendering process so that you can render the tooltip in your own custom way.

- Method Detail
  - onExternal
```
void onExternal(IsChart chart,
                TooltipModel model)
```
    External tooltips callback allows you to hook in the tooltip rendering process so that you can render the tooltip in your own custom way.
    
    Parameters:
    
    chart - chart instance
    
    model - all info about tooltip to create own HTML tooltip.