When a tooltip is set on to a JButton within a Frame (not JFrame),
it successfully displays any tips which either hangs outside of the window,
or lies above the border of the window.

However, if the pointer is positioned so that the whole tooltip is contained
within the Frame, no tooltip is displayed, and as soon as the mouse exits
out of the button, it throws a storm of exceptions:
(The following is repeated so many times that it quickly fills up the buffer)

Exception occurred during event dispatching:
java.lang.Error: Destination component not connected to component tree hierarchy
        at javax.swing.SwingUtilities.convertPoint(SwingUtilities.java:102)
        at javax.swing.DefaultPopupFactory$JPanelPopup.convertParentLocationToScreen(DefaultPopupFactory.java:1003)
        at javax.swing.DefaultPopupFactory$JPanelPopup.getBoundsOnScreen(DefaultPopupFactory.java:981)
        at javax.swing.ToolTipManager.mouseExited(ToolTipManager.java:472)
        at java.awt.AWTEventMulticaster.mouseExited(AWTEventMulticaster.java:254)
        at java.awt.Component.processMouseEvent(Component.java:3595)
        at java.awt.Component.processEvent(Component.java:3418)
        at java.awt.Container.processEvent(Container.java:1253)
        at java.awt.Component.dispatchEventImpl(Component.java:2506)
        at java.awt.Container.dispatchEventImpl(Container.java:1302)
        at java.awt.Component.dispatchEvent(Component.java:2420)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:2504)
        at java.awt.LightweightDispatcher.trackMouseEnterExit(Container.java:2366)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:2261)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2191)
        at java.awt.Container.dispatchEventImpl(Container.java:1289)
        at java.awt.Window.dispatchEventImpl(Window.java:854)
        at java.awt.Component.dispatchEvent(Component.java:2420)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:302)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:105)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:95)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:86)

I have attached a demo program. This works without any problem in JDK1.2.2.
The problem only became apparent with JDK1.3.

shinsuke.fukuda@Eng 1999-07-19