Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
*/
    private void removeItem(TreeItem item) {
        Object data = item.getData();
        if (data instanceof IPropertySheetEntry)
            ((IPropertySheetEntry) data)
                    .removePropertySheetEntryListener(entryListener);
        item.setData(null);
        item.dispose();
    }
    /**
     * Reset the selected properties to their default values.
     */
    public void resetProperties() {
        
        IStructuredSelection selection = (IStructuredSelection) getSelection();
        
        Iterator itr = selection.iterator();
        while (itr.hasNext())
            ((IPropertySheetEntry) itr.next()).resetPropertyValue();
    }
    /**
     * Sets the error message to be displayed in the status line.
     * 
     * @param errorMessage
     *            the message to be displayed, or <code>null</code>
     */
    private void setErrorMessage(String errorMessage) {
        
        if (statusLineManager != null)
            statusLineManager.setErrorMessage(errorMessage);