I had a similar ArrowCue-Problem, but it is not a "hefty bug", it is art :-)
You can reproduce the multiple arrows with your own SL-Demo "Tree to Grid Drag".
Add to the "OnOrderDragQuery"-Method after "e.Options.Payload = selectedItems"
the following line:
e.Options.ArrowCue = RadDragAndDropManager.GenerateArrowCue();
This will reproduce the problem. I have looked at your (Telerik) source code
to find out the cause.
Every RadDragAndDropManager.GenerateArrowCue() generates a new object.
Referring to your documentation this usually happens in the OnDragQuery
(like in your modified Demo) event handler.
In the source code (not of the demo, I mean the source code of the controls) you
find in RadDragAndDropManager.cs the method "PositionArrow()". In this method
every call adds the ArrowCue-Object to the Grid. The "If...Children.Contains..." condition
do not consider the fact, that almost on every call Options.ArrowCue is a new object.
I found a method "ResetEverything" which removes only the current ArrowCue-object
from the grid, not all.
Workaround: Call RadDragAndDropManager.GenerateArrowCue() only once per complete
The "second bug" Paul described (drag-and-drop-starting-on-scrollbar-slider.jpg) is
probably caused by the fact, that he must set the AllowDrag-Property to the GridViewRow,
not to the GridView.
The "third bug" he reported is indeed a problem (for me too), but I am not sure if it
is a normal behavior or a real bug.The default behavior of the grid in the
SelectionMode="Extended" is to select the hovered item. But in "Drag-State" this
behavior is not very desirable.