Allow mouse interaction with series input

The custom input handling for series prevents mouse interaction with GraphsView. There should be a way to allow this.

This kind of functionality is needed, for example, if one wants to draw a line on top of GraphsView when a mouse is dragged over the view area, then it only works when the MouseArea is placed outside the GraphsView and preventStealing is set to true. But this way the onPressed for the series points is not triggered. Attached example shows this behavior.