Overriding the Edit Control Functionality in Dash Leaflet

This is a demo Dash Leaflet app (built in Python 3.12) that shows how to programmatically implement the EditControl functionality. This is a somewhat simplified example, but you could of course mix and match the controls I've implemented here and extend it to include draw modes other than just markers.

The advantages I obtained from this implementation are:

• The EditControl buttons may not be obvious to some users, and for an app whose primary purpose is not to be a map viewer/editor, I didn't want to 'train' the user in how to interact with the map. By creating standard buttons, there is a very obvious route for how to interact with the map.
• The "Delete Mode" switch allows you to delete markers without having to also click "Save", as is required in the native EditControl button (this was important for my project, where a user was dealing with a small number of markers, and the added button click was intrusive to the workflow).
• We also had an associated DivMarker for each marker, to display a number alongside the marker, and when using Dash Leaflet's EditControl to delete markers, we couldn't delete the associated DivMarker until the user saved their deletion changes, which was confusing to the users.
• For completeness, I included the "Clear all markers" button, although this only slightly simplifies that action compared to the native EditControl workflow (by reducing from two button clicks to one, although it's still nice to have a big standout button for this).

Here is a screenshot of the demo app: