/**
  * Removes the items from all series for a given x value.
  *
  * @param x the x-value.
  */
 public void removeAllValuesForX(Number x) {
   if (x == null) {
     throw new IllegalArgumentException("Null 'x' argument.");
   }
   boolean savedState = this.propagateEvents;
   this.propagateEvents = false;
   for (int s = 0; s < this.data.size(); s++) {
     XYSeries series = (XYSeries) this.data.get(s);
     series.remove(x);
   }
   this.propagateEvents = savedState;
   this.xPoints.remove(x);
   fireDatasetChanged();
 }