Bug 183308 IllegalArgumentException occurs after insert a empty group on a List report item[0001]
Description: IllegalArgumentException occurs after insert a empty group on a List report item[0001] Build number: 2.2.0.v20070419-0945 Steps to reproduce: 1, Insert a list 2, Insert a group on the list, only specify the Group On: "aa" Expected result: No exception Actual result: IllegalArgumentException occurs Error log: java.lang.IllegalArgumentException: Argument cannot be null at org.eclipse.swt.SWT.error(SWT.java:3483) at org.eclipse.swt.SWT.error(SWT.java:3422) at org.eclipse.swt.SWT.error(SWT.java:3393) at org.eclipse.swt.widgets.Widget.error(Widget.java:432) at org.eclipse.swt.widgets.Text.setText(Text.java:1793) at org.eclipse.birt.report.designer.ui.dialogs.GroupDialog$6.focusLost(GroupDialog.java:485) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:136) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:962)
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/GroupDialog.java
tocArea.setLayout( UIUtil.createGridLayoutWithoutMargin( 2, false ) );
		
		tocEditor = new Text( tocArea, SWT.SINGLE | SWT.BORDER );
		GridData gd = new GridData( );
		gd.widthHint = 200;
		tocEditor.setLayoutData( gd );
		tocEditor.addModifyListener( new ModifyListener( ) {
			public void modifyText( ModifyEvent e )
			{
				if ( tocStyleType == null )
					return;
				if ( tocEditor.getText( ).trim( ).equals( "" ) ) 
				{
					tocStyleType.setEnabled( false );
				}
				else
				{
					tocStyleType.setEnabled( true );
				}
			}
		} );
		Button exprButton = new Button( tocArea, SWT.PUSH );
		
		setExpressionButtonImage( exprButton );
		exprButton.setToolTipText( Messages.getString( "GroupDialog.toolTipText.openExprButton" ) );
		exprButton.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent event )
			{
				ExpressionBuilder expressionBuilder = new ExpressionBuilder( tocEditor.getText( ) );
				expressionBuilder.setExpressionProvier( new ExpressionProvider( inputGroup ) );