Re: workable solution to non-focusable JWindow

Hi folks,

I've been wanting to have a stays on top toolbar for an app that I am
writing. I naturally don't want the toolbar to have its own button on
the windows taskbar, which is what a JFrame gives you, even if it is
undecorated. And a JDialog doesn't allow you to set alwaysOnTop.

The solution seems to be to use a JWindow, and this was working fine
until I wanted to put a JTextComponent in the toolbar. Unfortunately, a
JWindow by default will not be focusable, unless the parent JFrame is
showing, and this means that you will not be able to type into the
JTextComponent in the toolbar.

In may case, however, it was not as simple as just making sure that my
parent JFrame was visible. I'm using Spring Rich Client, and am able to
have multiple active windows, and close them off one by one (in any
order), until the last one is gone. So, if I make my first application
window JFrame the parent of my toolbar, when I close it, I lose
focusability in the toolbar.

I did a fair amount of searching, and saw a lot of people complaining
about the focusable nature of JWindow dating back to 2000/2001, but not
a lot since then. However, I never really found anyone offering a good
solution, either.

Here is what I came up with, for the use of anyone who cares in the future.

Recap of requirements:

A toolbar that must stay on top, must have a focusable
JTextComponent/JTextField in it, and must not create its own entry in
the Windows TaskBar. It must also be able to be independent of a
particular JFrame, since they may be closed at any time.

Solution:

public class ToolBar extends JWindow {

    public ToolBar() {
        super(new JFrame() {
            public boolean isShowing() { return true; }
        });
        setAlwaysOnTop(true);
        setFocusableWindowState(true);
        getContentPane().setLayout(new BorderLayout());

        final Point origin = new Point();
        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                origin.x = e.getX();
                origin.y = e.getY();
            }
        });
        addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent e) {
                Point p = getLocation();
                setLocation(p.x + e.getX()- origin.x,
                    p.y + e.getY() - origin.y);
            }
        });
    }

}

The key is the super() call in the constructor.
Window.isFocusableWindow() is final, otherwise we could simply override
it to return true at all times. So, we have to manipulate things a
little. Fortunately, Window.isFocusableWindow() contains the following
code:

  if (owner instanceof Frame || owner instanceof Dialog) {
      return owner.isShowing();
  }

Which means that if we can make sure that the owner always returns true
for isShowing(), we're set. Remember, however, that we don't want
unnecessary taskbar buttons, or other screen debris. So we can't just
use a JFrame and make it visible.

So, we subclass JFrame, and make it always return true for isShowing(),
even when it isn't, Window.isFocusableWindow() returns true, and our
JTextComponent can get focus.

Happiness!

Of course, I wonder if I have done things the difficult way. Can anyone
see an easier/cleaner way that achieves all the above objectives?

Regards,

Rogan