Justin Lee is on the right direction - the style we need to modify in order to change the content displayed in the tool tip when dragging or resizing an event in the RadGanttView is the GanttDragResizeVisualCueStyle. However in order to achieve this we need to change the DragTemplate and the ResizeTemplate of this style.
Please find attached a sample project demonstrating this customizations. What I did is to modify these templates and style to display only the Title of a GanttTask when dragging or resizing. Please note that this project uses implicit styles.
Hopefully this helps. Should you have any other problems or concerns do not hesitate to contact us again.
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