ingrid.yao@Eng 1997-08-08

Oracle showstopper bug#523611:
==================================
If, in a FOCUS_GAINED handler for a lightweight component, you try
to call requestFocus() to shift the focus to another view, the
request fails.
The problem is, I believe, in LightweightDispatcher.setFocusRequest,
in the code:
     
if (focusOwner == nativeContainer) {
  // This container already has focus so just
  // send FOCUS_GAINED event to lightweight component
  c.dispatchEvent(new FocusEvent(c, FocusEvent.FOCUS_GAINED ... )
  peerNeedsRequest = false;
}
The problem is that "focus" isn't yet set to "c" - that
doesn't happen until the end of the function. But this means
that, when focusRequest() is called inside of the FOCUS_GAINED
handler, the LightweightDispatcher might think the requestFocus()
is being invoked on the component that already has the focus,
in which case it ignores the request.
 
TESTCASE
===============
                       
Code to repro the problem follows. The code tries to keep
focus on #2. Note that if FocusComp is changed to extend
Canvas instead of Component, the given code works fine.
    
import java.awt.*;
import java.awt.event.*;
public class FocusBug extends Frame implements FocusListener
{
  public static void main(String[] args)
  {
    new FocusBug();
  }
  public FocusBug()
  {
    super();
    setLayout(new FlowLayout());
    _c1 = new FocusComp("#1");
    _c1.addFocusListener(this);
    _c2 = new FocusComp("#2");
    add(_c1);
    add(_c2);
    pack();
    setVisible(true);
  }
  public void focusGained(FocusEvent e)
  {
    _c2.requestFocus();
  }
  public void focusLost(FocusEvent e) {}
  private Component _c1;
  private Component _c2;
}
class FocusComp extends Component implements FocusListener
{
  public FocusComp(String name)
  {
    super();
    addFocusListener(this);
    setName(name);
    setSize(10, 10);
  }
  public boolean isFocusTraversable()
  {
    return true;
  }
  public void focusGained(FocusEvent e)
  {
    System.out.println(e);
  }
  public void focusLost(FocusEvent e)
  {
    System.out.println(e);
  }
}