Drag Drop Within WPF ToolWindow in VS2010 Extension Not Allowed

Question

I have a strange problem here. I've created a simple plugin using the wizard for a Visual Studio Integration Package / VSIX project with a tool window. Within that window I want to do a simple drag/drop from a listbox and drop within the same window. I've done the same thing in a normal WPF program, but when I do this in a WS toolwindow it's not allowed. I start the drag/drop operation (initiated by a PreviewMouseLeftButtonDown event) and call the DragDrop.DoDragDrop() method, I get the stop-sign-cursor at once. No dragging allowed.

Any ideas? Security restrictions or an effect of the fact that these WPF controls are hosted inside a ToolWindowPane and old Visual Studio IDE COM stuff I guess... Thanks for any help!

Answer 1

Alin Constantin at Microsoft helped me out here and has even written a blog post on how to do drag/drop within VS2010 properly!

http://alinconstantin.blogspot.com/2010/02/drag-and-drop-in-visual-studio-2010.html

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Highlights, in case of link rot:

In your tool window (the UserControl), override OnDragEnter, OnDragOver (important!) and OnDrop. Failure to override OnDragOver will cause drag/drop to fail.

In OnDragEnter, do the following:

1. Check to see if you can handle the drop
2. If so, set DragEventArgs.Handled to true and DragEventArgs.Effects to the appropriate value
3. Call base.OnDragEnter()

In OnDragOver, you must do the same thing as OnDragEnter. If you fail to set Handled, Visual Studio will take over and you won't be able to handle the drop!

In OnDrop,

1. Handle the drop
2. Set DragEventArgs.Handled to true
3. Call base.OnDrop()

Remember, not handling OnDragOver will result in Visual Studio taking over the drag operation, denying you the ability to handle it in OnDrop.