By refer to the title above, is that possible to display the percentage value for proportional stack type when the mouse pointer hover over the stack? Thank you.
Since info.valueFormatterFunction receives the values one by one the remaining option is to use info.advanced.contentsFunction. See this example: https://zoomcharts.com/developers/en/time-chart/examples/info-popup/contents-function.html
info.valueFormatterFunction
info.advanced.contentsFunction