Bug 153523 OK button in parameter dialog is enabled without default value in combo-box
Description: OK button in parameter dialog is enabled without default value in combo-box Steps to reproduce: 1. New a report parameter, combo-box. 2. Click New button, input abc as value, click OK 3. Set abc as default value and close Edit Parameter dialog. 4. New a data source and dataset 5. Edit the parameter, remove abc value and import values from dataset Expected result: OK button is disabled for there is no default value. Actual result: OK button is enabled.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
String columnName = getColumnName( inputParameter.getValueExpr( ) );
			if ( columnName != null )
			{
				columnChooser.setText( columnName );
			}
			columnName = getColumnName( inputParameter.getLabelExpr( ) );
			if ( columnName != null )
			{
				displayTextChooser.setText( columnName );
			}
			if ( defaultValue != null )
			{
				defaultValueEditor.setText( defaultValue );
			}
		}
		updateMessageLine( );
	}
	private void initFormatField( )
	{
		if ( ( DesignChoiceConstants.PARAM_TYPE_DECIMAL.equals( lastControlType ) && DesignChoiceConstants.PARAM_TYPE_FLOAT.equals( getSelectedDataType( ) ) )
				|| ( DesignChoiceConstants.PARAM_TYPE_FLOAT.equals( lastControlType ) && DesignChoiceConstants.PARAM_TYPE_DECIMAL.equals( getSelectedDataType( ) ) ) )
		{
			return;
		}
		IChoiceSet choiceSet = getFormatChoiceSet( getSelectedDataType( ) );
		if ( choiceSet == null )
		{
			formatCategroy = formatPattern = null;
		}
		else