Program: 188023
Project: 188023
Buggy source:
public void keyDownPressed(){
  ArrayList<Integer> temp=new ArrayList<Integer>();
  int last=selectedcollection.size() - 1;
  if (last < 0)   return;
  for (int j=0; j < selectedcollection.get(last).length; j++) {
    temp.add(new Integer(selectedcollection.get(last)[j]));
  }
  Item next=nextItem(getItem(temp,false));
  if (next != null && keypress != 2) {
    if (keypress != 1) {
      deselectAll();
      selectItem(next.getPos());
      if (next.getType() == 2 && next.getPos().size() == 1) {
        int userDefNr=next.getUserDefNr();
        Repository.window.mainpanel.p1.suitaDetails.setParent(next);
        if (userDefNr != Repository.window.mainpanel.p1.suitaDetails.getDefsNr()) {
          System.out.println("String_Node_Str" + next.getName() + "String_Node_Str"+ userDefNr+ "String_Node_Str"+ Repository.window.mainpanel.p1.suitaDetails.getDefsNr()+ "String_Node_Str");
        }
        try {
          for (int i=0; i < userDefNr; i++) {
            Repository.window.mainpanel.p1.suitaDetails.getDefPanel(i).setDescription(next.getUserDef(i)[1]);
          }
        }
 catch (        Exception e) {
          e.printStackTrace();
        }
      }
 else {
        Repository.window.mainpanel.p1.suitaDetails.setGlobalDetails();
        Repository.window.mainpanel.p1.suitaDetails.clearDefs();
        Repository.window.mainpanel.p1.suitaDetails.setParent(null);
      }
    }
 else {
      if (!clearedSelection) {
        deselectAll();
        clearedSelection=true;
        selectItem(getItem(temp,false).getPos());
      }
      if (next.isSelected()) {
        int[] itemselected=selectedcollection.get(selectedcollection.size() - 1);
        Item theone=Repository.getSuita(itemselected[0]);
        for (int j=1; j < itemselected.length; j++) {
          theone=theone.getSubItem(itemselected[j]);
        }
        theone.select(false);
        selectedcollection.remove(selectedcollection.size() - 1);
      }
 else       selectItem(next.getPos());
    }
    Repository.window.mainpanel.p1.remove.setEnabled(true);
    repaint();
  }
}

Fixed version (ground truth):
public void keyDownPressed(){
  ArrayList<Integer> temp=new ArrayList<Integer>();
  int last=selectedcollection.size() - 1;
  if (last < 0)   return;
  for (int j=0; j < selectedcollection.get(last).length; j++) {
    temp.add(new Integer(selectedcollection.get(last)[j]));
  }
  Item next=nextItem(getItem(temp,false));
  if (next != null && keypress != 2) {
    if (keypress != 1) {
      deselectAll();
      selectItem(next.getPos());
      if (next.getType() == 2 && next.getPos().size() == 1) {
        int userDefNr=next.getUserDefNr();
        Repository.window.mainpanel.p1.suitaDetails.setParent(next);
        if (userDefNr != Repository.window.mainpanel.p1.suitaDetails.getDefsNr()) {
          System.out.println("String_Node_Str" + next.getName() + "String_Node_Str"+ userDefNr+ "String_Node_Str"+ Repository.window.mainpanel.p1.suitaDetails.getDefsNr()+ "String_Node_Str");
        }
        try {
          for (int i=0; i < userDefNr; i++) {
            Repository.window.mainpanel.p1.suitaDetails.getDefPanel(i).setDescription(next.getUserDef(i)[1],true);
          }
        }
 catch (        Exception e) {
          e.printStackTrace();
        }
      }
 else {
        Repository.window.mainpanel.p1.suitaDetails.setGlobalDetails();
        Repository.window.mainpanel.p1.suitaDetails.clearDefs();
        Repository.window.mainpanel.p1.suitaDetails.setParent(null);
      }
    }
 else {
      if (!clearedSelection) {
        deselectAll();
        clearedSelection=true;
        selectItem(getItem(temp,false).getPos());
      }
      if (next.isSelected()) {
        int[] itemselected=selectedcollection.get(selectedcollection.size() - 1);
        Item theone=Repository.getSuita(itemselected[0]);
        for (int j=1; j < itemselected.length; j++) {
          theone=theone.getSubItem(itemselected[j]);
        }
        theone.select(false);
        selectedcollection.remove(selectedcollection.size() - 1);
      }
 else       selectItem(next.getPos());
    }
    Repository.window.mainpanel.p1.remove.setEnabled(true);
    repaint();
  }
}