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
else
				throw e;
		}
		if ( monitor.isCanceled( ) )
			throw new OperationCanceledException( );
	}
	/**
	 * @return Report Designer UI plugin installation directory as OS string.
	 */
	public static String getHomeDirectory( )
	{
		URL url = ReportPlugin.getDefault( ).getBundle( ).getEntry( "/" ); 
		String home = null;
		try
		{
			home = Platform.resolve( url ).getPath( );
		}
		catch ( IOException e )
		{
			logger.log(Level.SEVERE, e.getMessage(),e);
		}
		return home;
	}
	/**
	 * @return Report Designer UI plugin installation directory as OS string.
	 */
	public static String getFragmentDirectory( )
	{
		Bundle bundle = Platform.getBundle( IResourceLocator.FRAGMENT_RESOURCE_HOST );
		if ( bundle == null )