Generate popup when we double click any object

GoJS
1

on doubleclick any object in the diagram it should show a popup with three option form1, form2, form3,
and when we click any of the form it should show form detail regarding that object.

2

Implement the GraphObject.doubleClick event handler or “ObjectDoubleClicked” DiagramEvent listener. That can show a dialog using whatever mechanisms your framework uses.

3

i have used doubleclick event listener in that but the logic i am not getting how to show popup when doubleclick or contextmenu in that with different option.

4

This example is given in Page Not Found -- Northwoods Software
click: function(e, obj) { showMessage("Clicked on " + obj.part.data.key); }

obj is the GraphObject where the click or doubleClick event handler is declared.
obj.part is the Part, in this case the Node, that the user is clicking on.
obj.part.data is the model data object with all of your data properties that are specific to that node.