[Feature] Draggable tags

[ntftrader]

Feature Description

Feature request (or implementation advice). See also #282 and #251

The screenshot shows an example programmatically using Tag for chart trading (bracket trading). However Tag do not have any drag/drop or other callbacks like Shape but has the essential layout both mark, price indicator and full length line.

To Do

1. Could Tag inherit from Shape instead?
2. Or should there be a custom inherited from Shape like DraggableTag?

[lihu]

V9-alpha has been released. You can try to createOverlay('simpleTag') or customize overlay.