ui/src/main/java/ucar/util/prefs/ui/ComboBox.java
public void addItem( Object item) {
    if (item == null) return;
    for (int i=0; i<getItemCount(); i++) {
      if (item.equals( getItemAt(i))) {
        if (i == 0) {
          setSelectedIndex(0);
          return; // already there
        }
        removeItemAt(i);
      }
    }

    // add as first in the list
    insertItemAt( item, 0);
    setSelectedIndex(0);
  }
public void addItem( Object item) {
    if (item == null) return;
    for (int i=0; i<getItemCount(); i++) {
      if (item.equals( getItemAt(i))) {
        if (i == 0) {
          setSelectedIndex(0);
          return; // already there
        }
        removeItemAt(i);
      }
    }

    // add as first in the list
    insertItemAt( item, 0);
    setSelectedIndex(0);
  }
Add the item to the top of the list. If it already exists, move it to the top.
@param item to be added.