Add option to specify Marker's shadow pane

[cherniavskii]

Issue description extracted from #6312

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How to reproduce

Environment

• Leaflet 1.3.4
• Firefox 61, Chrome 68

Steps

1. Create a custom pane (Pane A) with z-index 300.
2. Create a Marker and specify that it should be added to Pane A.
3. Create a custom pane (Pane B) with z-index 301.
4. Create an opaque Rectangle with coordinates/dimensions that overlap the Marker, and specify that the rectangle should be added to Pane B.

What behavior I'm expecting and which behavior I'm seeing

Expected: the marker+shadow in Pane A to be hidden by the rectangle in Pane B, which has a higher z-index.

Actual: the marker's shadow in Pane A is still visible. This is happening because Marker.js:254 is hard-coded to alway add a marker's shadow icon to the shadowPane.

Minimal example reproducing the issue

• this example is as simple as possible
• this example does not rely on any third party code

Example: https://plnkr.co/edit/PwS1sNmAfqAXIydn1lFW?p=preview

[cherniavskii]

My suggestion is to add a shadowPane option to Marker, so that developers can specify pane for marker's shadow. The default behavior will remain the same - we don't want to break someone's app :)

[ldaws003]

Hi, is this issue still open, and if so mind if I take a look and try to fix it?

[cherniavskii]

Hi Leon,
This issue is still opened, but it's already addressed in #6460

Feel free to explore other issues under good first issue label

[cherniavskii]

Closed by #6460