Bug 166315 Combo box doesn't allow blank when set string type in parameter editor
Combo box doesn't allow blank when set string type in parameter editor Steps to reproduce: 1.New a parameter, display type is Combo Box 2.Select data type as String Expected result: "Allow blank values" is enable. Actual result: "Allow blank values" is gray and can't be checked.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
{
		createLabel( valueArea, LABEL_DEFAULT_VALUE );
		defaultValueEditor = new Text( valueArea, SWT.BORDER );
		defaultValueEditor.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		defaultValueEditor.addModifyListener( new ModifyListener( ) {
			public void modifyText( ModifyEvent e )
			{
				changeDefaultValue( UIUtil.convertToModelString( defaultValueEditor.getText( ),
						false ) );
				if ( isStatic( ) )
				{
					refreshValueTable( );
				}
			}
		} );
	}
	private void createPromptLine( Composite parent )
	{
		promptMessageLine = new Label( parent, SWT.NONE );
		promptMessageLine.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
	}
	protected void okPressed( )
	{
		try
		{
			
			inputParameter.setName( nameEditor.getText( ) );
			inputParameter.setPromptText( UIUtil.convertToModelString( promptTextEditor.getText( ),
					true ) );
			String newControlType = getSelectedControlType( );