Drag and Drop not work in Firefox

[tfMovamo]

Drag and Drop not work in Firefox 65.0

[LeifAndersen]

drag and drop still appears to not work in the most modern version of firefox either.

[LeifAndersen]

Looks like its because firefox does not support onDragStart for svg elements: https://bugzilla.mozilla.org/show_bug.cgi?id=691796

That's unfortunate. I suspect we'll have to insert foreign objects as spans to get it to work.

[LeifAndersen]

Okay, this PR #70 addresses (although does not completely solve) the issue.

[jannikbuschke]

The referenced bug seems to be closed on firefox side. Maybe someone can test again with version 2.0.0-beta.2 or higher.