ToolTips
RadTaskbarButton exposes Microsoft API to set tooltip text on its thumbnail preview container or its thumbnail buttons.
Figure 1: ThumbnailTooltip
To set a ToolTip on the thumbnail preview part of the control, you can use the ThumbnailTooltip property of RadTaskbarButton.
this.radTaskbarButton1.ThumbnailTooltip = "My RadTaskbar Button ToolTip";
Me.RadTaskbarButton1.ThumbnailTooltip = "My RadTaskbar Button ToolTip"
To set ToolTip to the thumbnail buttons, you can directly use their ToolTip property.
this.radTaskbarButton1.ThumbnailButtons[1].ToolTip = "Telerik WinForms";
Me.RadTaskbarButton1.ThumbnailButtons[1].ToolTip = "Telerik WinForms"