I'm currently on version 2011 Q3, so I have the DragDropManager, but it doesn't look like I have PayloadManager capability. I have some screenshots of the way it's been working with RadDragAndDropManager, but I'm still trying to figure out how to attach them.
When you drag the grid rows, you can see the list of items (I have a datatemplate for that) and a Drag Cue. The Drag Cue shows a "No" symbol when you can't drop (over the grid and over portions of the TreeView where dropping is not allowed), or text that we change based on which button you are pushing (currently set in DropQuery):
TreeViewDragCue cue = (e.Options.DragCue as TreeViewDragCue);
ModifierKeys keys = Keyboard.Modifiers;
bool shiftKey = (keys & ModifierKeys.Shift) != 0;
bool controlKey = (keys & ModifierKeys.Control) != 0;
cue.DragActionContent = controlKey ? "Copy to Folder" : (shiftKey ? "Move to Folder" : "Add to Folder");
This is working for dragging (and not dropping) in the grid, and is giving correct cues for RadBreadcrumbBarItems when I attach DropQuery/DropItem to the BreadCrumbBar, but it is NOT working for RadTreeViewItems, because the drop is considered to be on the RadTreeView, not on the items.
As I stated before, I've been trying to work around all that. My initial attempt at DragDropManager has run up against a lot of incomplete or unhelpful documentation, and here are my remaining issues:
1) I'm having problems getting my dragged files to appear. I'm setting e.Data to a List, and e.DragVisual to a DragVisual object with the e.Data as Content and a DataTemplate as the ContentTemplate. Is that DataTemplate supposed to include a structure for displaying that List, or should it just be a per-item DataTemplate?
2) I don't understand how to get a DragCue (other than what looks like the standard MS drag cue) to appear so that I can see the big red "No" circle or my special drag cue text.
3) The grid rows aren't showing the standard MS "no drag" cue -- instead they act like you can drop on them. This might be because I am allowing File Drop in that region, but it wasn't happening before.
All in all, I'm not impressed with DragDropManager. I much prefer the RadDragAndDropManager -- it's much prettier. I just want it to work with my RadTreeViewItems!