Is Java Access Bridge (JAB) thread-safe, regarding Swing access outside EDT?

Is Java Access Bridge (JAB) thread-safe, regarding Swing access outside EDT?

I am using Jedit, java text editor. When I switch on accessibility and
open Java Ferret, strange things happen to java application gui. When I
walk up and down the combo box of Buffer Switcher, the labels appear in
wrong places. It's enough to close Java Ferret to make it work ok again.
I suspect that JAB makes unsafe calls to EDT. That's an exception output I
got (on another control):
Exception in thread "Thread-2" 10:17:35 [Thread-2] [error] Thread-2:
java.lang.NullPointerException
10:17:35 [Thread-2] [error] Thread-2: at
javax.swing.JLabel.setIcon(Unknown Source)
10:17:35 [Thread-2] [error] Thread-2: at
sidekick.enhanced.SourceTree$Renderer.configureTreeCellRendererComponent(SourceTree.java:243)
10:17:35 [Thread-2] [error] Thread-2: at
org.gjt.sp.util.EnhancedTreeCellRenderer.getTreeCellRendererComponent(EnhancedTreeCellRenderer.java:105)
10:17:35 [Thread-2] [error] Thread-2: at
com.sun.java.accessibility.AccessBridge$AccessibleJTreeNode.getCurrentComponent(AccessBridge.java:5396)
10:17:35 [Thread-2] [error] Thread-2: at
com.sun.java.accessibility.AccessBridge$AccessibleJTreeNode.getCurrentAccessibleContext(AccessBridge.java:5371)
10:17:35 [Thread-2] [error] Thread-2: at
com.sun.java.accessibility.AccessBridge$AccessibleJTreeNode.getAccessibleName(AccessBridge.java:5416)
10:17:35 [Thread-2] [error] Thread-2: at
com.sun.java.accessibility.AccessBridge.getAccessibleNameFromContext(AccessBridge.java:695)
10:17:35 [Thread-2] [error] Thread-2: at
com.sun.java.accessibility.AccessBridge.run(Native Method)
10:17:35 [Thread-2] [error] Thread-2: at java.lang.Thread.run(Unknown
Source)
Tried to submit this as a bug report to bugs.sun.com, but this page sucks.
After 3 unsuccessful attempts to submit a report (Submission Error) I
wrote to bug-reportform-error-page@sun.com as suggested. Answer:
Diagnostic-Code: smtp; 550 5.1.1 <bug-reportform-error-page@sun.com>...
User unknown
I started making Jedit accessible, but if JAB is a crap, this work may be
pointless and should be abandoned as quickly as possible. Please give a
general advice, if it makes sense as an answer.