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/CascadingParametersDialog.java
allowNull.setSelection( selectedParameter.allowNull( ) );
		changeDataType( selectedParameter.getDataType( ) );
		loading = false;
	}
	private void clearParamProperties( )
	{
		paramNameEditor.setText( "" ); 
		promptText.setText( "" ); 
		dataTypeChooser.select( -1 );
		displayTypeChooser.select( -1 );
		defaultValueEditor.setText( "" ); 
		helpTextEditor.setText( "" ); 
		formatField.setText( "" ); 
		listLimit.setText( "" ); 
		previewLable.setText( "" ); 
		allowNull.setSelection( false );
	}
	private void setControlEnabled( boolean enable )
	{
		paramNameEditor.setEnabled( enable );
		promptText.setEnabled( enable );
		dataTypeChooser.setEnabled( enable );
		displayTypeChooser.setEnabled( enable );
		defaultValueEditor.setEnabled( enable );
		helpTextEditor.setEnabled( enable );
		formatField.setEnabled( enable );
		listLimit.setEnabled( enable );
		changeFormat.setEnabled( enable );
	}
	private void changeDataType( String type )