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
if ( part instanceof GridEditPart )
			return null;
		return part;
	}
	/**
	 * Returns list editpart.
	 * 
	 * @param editParts
	 *            a list of editpart
	 * @return the current selected list editpart, null if no list editpart,
	 *         more than one list, or other list editpart. List band editpart is
	 *         also a type of list editpart.
	 */
	public static ListEditPart getListEditPart( List editParts )
	{
		if ( editParts == null || editParts.isEmpty( ) )
			return null;
		int size = editParts.size( );
		ListEditPart part = null;
		for ( int i = 0; i < size; i++ )
		{
			Object obj = editParts.get( i );
			ListEditPart currentEditPart = null;
			if ( obj instanceof ListEditPart )
			{
				currentEditPart = (ListEditPart) obj;
			}
			else if ( obj instanceof ListBandEditPart )
			{
				currentEditPart = (ListEditPart) ( (ListBandEditPart) obj ).getParent( );