In editor/www/doc/Proposals/Tooltip/UsersView.html the sample code
for tooltip computation is not asynchronous - it calls doc.render,
and doc.render turns right around and calls run() from the same
thread so by the end of the call we return the string, not null,
from getShortDescription().

When I implement this asynchronously, such that getShortDescription
just returns null and a second later we set the tooltip text,
things don't seem to work (or, perhaps my code for setting the
text/visibility isn't right?)       All I see is a small black line
near the cursor (where the tooltip should be) - and that's only
the first time I hover over text - the second time I see nothing.

Here's a very basic program which shows this: add this as your tooltip
computation class (I'll add it as an attachment too, but I've had
problems with issuezilla and attachments in the past so I'm inlining
it as well:


package com.sun.forte.developer.ipe.debugger;

import java.lang.Thread;
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
import java.io.*;

import org.openide.text.*;
import org.openide.util.RequestProcessor;

public class EvalAnnotationOriginal extends Annotation {
    
    public String getShortDescription() {
	RequestProcessor.postRequest (new Runnable () {
		public void run () {
		    SwingUtilities.invokeLater(new Runnable () {
			    public void run () {
				try {
				    Thread.sleep(1000);
				    run2();
				} catch (Exception e) {
				    e.printStackTrace();
				}
			    }
			});
		}
	    });
	return null;
    }
    
    public void run2() {
	firePropertyChange(PROP_SHORT_DESCRIPTION,
			   null, "Delayed Result");
    }

    public String getAnnotationType() {
	return null; // Currently return null annotation type
    }
}

All the program does is basically return null from getShortDescription,
and then arrange for the short description property to be updated 1 second
later asynchronously.