Stunner - Line Splicing dragging Nodes directly from palette

Currently, in order to perform the line splicing the user has to first drop the node from the palette into the canvas and then drag-and-drop it over a connector in between to connected nodes.

It should be also possible to directly drag-and-drop a node from the palette over a connector in between to connected nodes and get the line splicing executed if the connection is allowed making it more intuitive for the user.

Acceptance Criteria:

• The user drags a node from the palette and drop it over a connector in between to connected nodes and the line splicing is performed if the the connection between the three nodes involved is allowed.