[Feature] Better visibility for overlapping items on gantt chart

[JettFDR]

What problem does this feature solve?

I have searched through all of the forums, documentation and tried messing with the logic of the gantt chart but I have yet to discover a good way of handling data that share the same time frame and row without entirely breaking the existing logic.

From what I've found, the default behaviour currently just hides the items behind each other, which can be quite limiting and there doesn't seem to be any options to change this.

Here is an example using the custom-gantt chart example.
Moving the item to the row below:

Item on the row below, blending together with the other items:

What does the proposed API look like?

This could be resolved with some sort of stacking behaviour to increase the height of the row when there are multiple items occupying the same space. I have quickly put together a rough of image of what I mean below:

I have tried to create this feature by modifying the the gantt chart's logic with no success.
I will continue to try and find work arounds for this scenario, but an official method would be greatly appreciated.

Have been loving the Echarts environment so far and look forward to all future improvements.