I am really sorry to hear about your disappointment.
The issue with the DragPreviewTooltip you encounter with the 2009.1 526 .dll versions are solved in the new version of our controls. You can test the new DragAndDrop functionality of the RadTreeView in the attached project:WpfEDM_2010_1_603.35 where I used our latest WPF binaries - 2010.1.603.35. In this version of the controls the DragPreviewTooltip uses the ItemTemplate set to each dragged item to determine what to display.
However, I also updated the project you sent by overriding the ToString() method of the business classes so that it can return Name. In the 2009.1.526 version of the controls the ToSting() method of the displayed business object is used to determine what to be displayed in the DragPreviewTooltip.
I also added a new property to the Categorie class - SubCategories as ObservableCollection(Of SubCategorie) and modified the LoadDB method to populate this observable collection. I made this modification because the EntitiCollection SubCategorie doesn't implement INotifyCollectionChanged, which was causing issues with the drag and drop. You can also take a look at this help article describing how to bind the RadTreeView to a WCF service
and to Ado .NET data service
Also I commented the PreviewDragEnded, DragEnded and PreviewDragStarted event handlers so that you can see the default DragAndDrop functionality of the RadTreeView.
Please find attached a project with the 2009.1.526 version of the controls as well as one with the 2010.1.603.35. Give them a try and let me know if they work for you or if your scenario requires a different approach.
Also, you said you need to apply certain limitations to the drag ad drop functionality, so if you encounter any issues, please elaborate on your scenario requirements and we will be more than happy to provide you with a more suitable solution.
Also you can take a look at the Help article on the DragAndDrop functionality of the RadTreeView
and also at this demo
If you need further assistance we will be more than happy to help.
the Telerik team
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