How to pin a diagram?


I want to pin a diagram + scroll the diagram with the mouse?
When the tree is expanded, the scrolling works fine, but when the tree is collapsed, the mouse will is moving the entire diagram.

collapsed (scrolling is bad):

expanded (scrolling is good):

This is the diagram definition:

  $(go.Diagram, "myTreeDiv",
	  "panningTool.isEnabled": false,
      allowMove: false,
      allowCopy: false,
      allowZoom: false,
      allowDelete: false,
      allowHorizontalScroll: true,
      allowVerticalScroll: true,
            alignment: go.TreeLayout.AlignmentStart,
            angle: 0,
            compaction: go.TreeLayout.CompactionNone,
            layerSpacing: 15,
            layerSpacingParentOverlap: 1,
            nodeIndent: 3,
            nodeIndentPastParent: 1,
            nodeSpacing: 5,
            setsPortSpot: false,
            setsChildPortSpot: false

You should probably be setting Diagram.contentAlignment if you want the content to be pinned. Setting this to something like go.Spot.TopLeft should resolve the scroll issue.