I have a control that draws a diagram, and I show a tooltip when the user is hover an object.
I have also implemented the functionality to show a context menu when you right click the object.
The logic for showing the tooltip is OnMouseMove(), but the contextmenu is associated to the control, so its shown by .NET.
The problem is that when I show the context menu, then is shown the tooltip hover the context menu.
You could use ContextMenu.PopUp Event in conjunction with the ToolTip.Active Property so that every time your context menu is being shown, you will deactivate the tooltips for the controls.