Bug 192349 The column selected disappears when you reclick the downward arrow [0001]
Description: The column selected disappears when you reclick the downward arrow. Build number: 2.2.0.v20070613-1211 Steps to reproduce: 1, New a table binding to a data set, add an Aggregation, select one column from the "Data Field" dropdown list, click the downward arrow again. Expected result: The column selected is still there. Actual result: The column selected disappears. Error log: N/A
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/BindingDialogHelper.java
{
		new Label( composite, SWT.NONE ).setText( EXPRESSION );
		txtExpression = new Text( composite, SWT.BORDER );
		txtExpression.setLayoutData( new GridData( GridData.FILL_HORIZONTAL
				| GridData.GRAB_HORIZONTAL ) );
		createExpressionButton( composite, txtExpression );
		txtExpression.addModifyListener( new ModifyListener( ) {
			public void modifyText( ModifyEvent e )
			{
				verifyInput( );
			}
		} );
	}
	private void verifyInput( )
	{
		if ( txtName != null
				&& ( txtName.getText( ) == null || txtName.getText( )
						.trim( )
						.equals( "" ) ) ) 
		{
			if ( dialog.getOkButton( ) != null )
				dialog.getOkButton( ).setEnabled( false );
		}
		else if ( txtExpression != null
				&& ( txtExpression.getText( ) == null || txtExpression.getText( )
						.trim( )
						.equals( "" ) ) ) 
		{
			if ( dialog.getOkButton( ) != null )
				dialog.getOkButton( ).setEnabled( false );