Bug 90528 Editor icon does not show problem decoration for second instance
3.1 M6 - open a .java file that has errors or warnings - the editor tab icon has the problem decoration - Window > New Window - open the same file in the new window - the editor tab icon is missing the problem decoration
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
if (!forced && !progressMonitor.isCanceled()) {
			Shell shell= getSite().getShell();
			if (shell != null && !shell.isDisposed()) {
				shell.getDisplay().asyncExec(new Runnable() {
					public void run() {
						selectionChanged();
					}
				});
			}
		}
	}
	
	/**
	 * Tells whether this is the active editor in the active page.
	 *
	 * @return <code>true</code> if this is the active editor in the active page
	 * @see IWorkbenchPage#getActiveEditor
	 */
	protected final boolean isActiveEditor() {
		IWorkbenchWindow window= getSite().getWorkbenchWindow();
		IWorkbenchPage page= window.getActivePage();
		if (page == null)
			return false;
		IEditorPart activeEditor= page.getActiveEditor();
		return activeEditor != null && activeEditor.equals(this);
	}
	
	/**
	 * Adds the given listener.
	 * Has no effect if an identical listener was not already registered.