Canvas retains previous screen pixels when moved to new location

(Sun bug ID: 4968008)

There is a bug using the Sun JVM:  The canvas used for a ToolTip usually gets painted with the proper background and text.  However, about 5% of the time this does not happen.  Instead, the pixels that should have been under the canvas in its previous location are used instead of the proper display.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.  Run the applet on this page.
2.  Hold the mouse pointer over one checkbox until the ToolTip appears.  Then move to the other checkbox.  Keep doing this.

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected:  The ToolTip should always display the pale yellow background and the ToolTip text.

Actual: About 5% of the time the new ToolTip canvas does not paint the ToolTip text.  Instead, the pixels that were covered by the ToolTip canvas in its previous location are displayed.

Behavior is always OK in other JREs, including Apple's MRJ 3.3 and Microsoft's JRE version 3809.

Adding update and validate/invalidate code does not overcome the bug.
 

If you have any comments about this test page please contact Mickey Segal.  A listing of  many Java resources is at this link.