Gets the horizontal position of the mouse.
Assembly: PresentationFramework (in PresentationFramework.dll)
When the user opens a context menu by right clicking the mouse, this property returns the position of the mouse. Specifying the position of the ContextMenu by setting the PlacementTarget, PlacementRectangle, Placement, HorizontalOffset, or VerticalOffsetProperty properties does not affect the value of .
When the user opens a context menu by using the keyboard, or when the context menu closes, the value of this property is -1.