A deadlock can be seen using 1.4.1_02 and Mantis-beta Java Plugin.
The testcase, source code and full threaddumps are located in the attachments.

The thread dump shows a classic deadlock with the
"applet-ScrollableTableApplet" thread making a call into
GridPanel.setBounds locking ScrollableTable but is stuck in a wait-on-monitor
state for the java.awt.Component$AWTTreeLock monitor held by the
"AWT-EventQueue-14" thread.

The "AWT-EventQueue-14" thread holds the java.awt.Component$AWTTreeLock monitor
while waiting for its turn to run the GridPanel.setBounds method.

I attached part of the thread dump below showns the threads and locks
involved:

Full thread dump Java HotSpot(TM) Client VM (1.4.1_02-b06 mixed mode):
Found one Java-level deadlock:
=============================
"AWT-EventQueue-14":
  waiting to lock monitor 0x27c6774 (object 0x543d020, a ScrollableTable),
  which is held by "thread applet-ScrollableTableApplet"
"thread applet-ScrollableTableApplet":
  waiting to lock monitor 0x27c6734 (object 0x5bb2450, a java.awt.Component$AWTT
reeLock),
  which is held by "AWT-EventQueue-14"

"AWT-EventQueue-14" prio=4 tid=0x027A9028 nid=0x110 waiting for monitor entry [2
0d9f000..20d9fd8c]
        at CoffeeTable.Grid.GridPanel.setBounds(GridPanel.java:1988)
        - waiting to lock <0543D020> (a ScrollableTable)
        at java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.java:1523)
        at java.awt.GridBagLayout.arrangeGrid(GridBagLayout.java:1336)
        at java.awt.GridBagLayout.layoutContainer(GridBagLayout.java:706)
        at java.awt.Container.layout(Container.java:1017)
        at java.awt.Container.doLayout(Container.java:1007)
        at java.awt.Container.validateTree(Container.java:1089)
        at java.awt.Container.validateTree(Container.java:1096)
        at java.awt.Container.validateTree(Container.java:1096)
        at java.awt.Container.validate(Container.java:1064)
        - locked <05BB2450> (a java.awt.Component$AWTTreeLock)
        at sun.plugin.AppletViewer$AppletEventListener.appletStateChanged(Applet
Viewer.java:503)

"thread applet-ScrollableTableApplet" prio=4 tid=0x026A6DF8 nid=0x2ec waiting fo
r monitor entry [1fb9f000..1fb9fd8c]
        at java.awt.Component.reshape(Component.java:1674)
        - waiting to lock <05BB2450> (a java.awt.Component$AWTTreeLock)
        at java.awt.Component.setBounds(Component.java:1665)
        at CoffeeTable.Grid.GridPanel.redoScrollbars(GridPanel.java:6743)
        at CoffeeTable.Grid.GridPanel.setBounds(GridPanel.java:1997)
        - locked <0543D020> (a ScrollableTable)
        at java.awt.Component.resize(Component.java:1602)
        at java.awt.Component.setSize(Component.java:1594)
        at ScrollableTableApplet.setGridSize(ScrollableTableApplet.java:1376)
        at ScrollableTableApplet.init(ScrollableTableApplet.java:285)
        at sun.applet.AppletPanel.run(AppletPanel.java:348)
        at java.lang.Thread.run(Thread.java:536)