Bug 69240 [reconciling] Editor shows "stale" compilation error
Eclipse has always has a small problem in that occaisionally it would show an error in the editor window (red-squiggly, with a marker) even though the error had been fixed and no longer appeared in the Tasks/Problem view. I usually just type "Space-Backspace" and save the file and it goes away. In 3.0, this is MUCH more frequent. I'm not 100% sure of the cause, but every time I've seen in it recently, file A will have a problem, and then I'll change file B to fix it. I'll pay more attention, and see if I can obtain any more details.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/JavaReconciler.java
* @see org.eclipse.jface.text.reconciler.MonoReconciler#process(org.eclipse.jface.text.reconciler.DirtyRegion)
	 */
	protected void process(DirtyRegion dirtyRegion) {
		 
		synchronized (fMutex) { 
			super.process(dirtyRegion);
		}
	}
	
	/**
	 * Tells whether the Java Model has changed or not.
	 * 
	 * @return <code>true</code> iff the Java Model has changed
	 * @since 3.0
	 */
	private synchronized boolean hasJavaModelChanged() {
		return fHasJavaModelChanged;
	}
	
	/**
	 * Sets whether the Java Model has changed or not.
	 * 
	 * @param state <code>true</code> iff the java model has changed
	 * @since 3.0
	 */
	private synchronized void setJavaModelChanged(boolean state) {
		fHasJavaModelChanged= state;
	}
}