only enabled for branches and markers, since in tasview we use rightclick to start advance/rewind.
involved some hackery, like killing context menu while OnMouseDown of the given listview, then going back to InputRoll's OnMouseDown and actually selecting a new cell. can we figure out a hovered cell while context menu is still active? also, it'd make sense to do this for leftclick as well, but without context menu hiding, there doesn't seem to be a way to force updating of listviews from InputRoll.
feos