Bug 175664 [Mac] Unexpected internal exception occurs when invoke expression builder
Description: There are two problems: 1. "fx" button (Click this button to invoke Expression Builder) could not be displayed correctly, nothing displayed in the button. 2. Click on the button, an unexpected internal exception occurs. Version:2.2.0.v20070205 Steps to reproduce: 1.Insert a Data item to the layout. Click "fx" button to invoke the expression builder, although on Mac "fx" button could not display correctly. Error log: Argument cannot be null Plug-in Provider: Eclipse.org Plug-in Name: BIRT Designer UI Plug-in ID: org.eclipse.birt.report.designer.ui Error Code: Error.GUIException.invokedByUnexpectedException Error Message:Argument cannot be null
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/util/UIUtil.java
* 
	 * @param id
	 *            the id of view part
	 * 
	 * @return Returns the view part, or null if not found
	 */
	public static IViewPart getView( String id )
	{
		IWorkbenchPage tPage = PlatformUI.getWorkbench( )
				.getActiveWorkbenchWindow( )
				.getActivePage( );
		IViewReference[] v = tPage.getViewReferences( );
		int i;
		for ( i = 0; i < v.length; i++ )
		{
			if ( v[i].getId( ).equals( id ) )
				return (IViewPart) v[i].getPart( true );
		}
		return null;
	}
	public static IEditorPart getEditor( String id )
	{
		IWorkbenchPage tPage = PlatformUI.getWorkbench( )
				.getActiveWorkbenchWindow( )
				.getActivePage( );
		if ( tPage == null )
			return null;
		IEditorReference[] v = tPage.getEditorReferences( );
		int i;
		for ( i = 0; i < v.length; i++ )