'Set the pen for drawing the line while the mouse hovers over it.
Allowable arguments are any that are valid
for :func:`mkPen <pyqtgraph.mkPen>`.
If the line is not movable, then hovering is also disabled.
Added in version 0.9.9.'

def setHoverPen(self, *args, **kwargs):

    self.hoverPen = fn.mkPen(*args, **kwargs)
    if self.mouseHovering:
        self.currentPen = self.hoverPen
        self.update()
