Hi Chris,
There are currently no plans to add the DragDrop class to Silverlight in the 2.0 time frame. It would however be possible to write code to achieve what you want to do, it would involve a bit of work however. In broad outline, the following is one approach you could take:
create the following:
class DraggableControl : UserControl
interface IDragDropTarget { OnControlDraggedInto(DraggableControl control, Point position); }
class DragDropStackPanel : StackPanel, IDragDropTarget
class DragDropGrid : Grid, IDragDropTarget
1. In DraggableControl.MouseLeftButtonDown call CaptureMouse.
2. In DraggableControl.MouseLeftButtonUp call ReleaseMouseCapture, determine if the mouse if over an IDragDropTarget by calling UIElement.HitTest on the root of the application using the current position of the mouse. If so, call OnControlDraggedInto on the IDragDropTarget, passing the control and the mouse position relative to the IDragDropTarget.
3. In both implementations of OnControlDraggedInto you will need to determine where in the Panel to insert the control. You can use LayoutInformation.GetLayoutSlot on the Panel's Children to determine where they are currently located (necessary for StackPanel) and you can use Grid.ColumnDefinitions
.ActualWidth/Grid.RowDefinitions
.ActualHeight to work it out for Grid.
Once you have determined where in the Panel to insert the DraggableControl, you will need to first remove the DraggableControl from its current Parent before adding it to the new one.
4. You can use DraggableControl to wrap any Control that you want to be able to drag and drop, so you probably want to expose DraggableControl.Child and use it to get/set UserControl.Content
This is only one approach that you could take. There are likely alternatives. For example, if you don't like the idea of having to subclass Grid and StackPanel you could use a static method to perform the calculations, switching based on the type of the target.
Let me know if this is helpful to you. If it is unclear let me know and I will try to explain in more detail.
Keith Mahoney
Silverlight SDET
Microsoft