Yahoo! Messenger Games plug-in

Yahoo! Messenger now gives users the ability to play YAP games directly from the world's most popular IM client. If you're a YAP game publisher, just run through this checklist to be sure your game is ready.

The Yahoo! Messenger Games Plug-in

Based on Internet Explorer web control, the Games Plug-in allows user to play YAP games from within Yahoo! Messenger.

Plug-in displays Featured Games icons and Recent Games icons, with Games Gallery and Options commandsYMessenger-Games

The Games Plug-in requires Yahoo! Messenger 11. If you are modifying an existing YAP game or actively developing a new one, please be sure to use the latest build of Messenger.

Supporting Internet Explorer

Your game must fully support IE6, IE7, and IE8. By default, the IE web control uses "Standard mode." So even if you have installed IE8, the web control will behave as if you are using IE7. It is therefore important to be sure your game is fully supported in IE7.

Still need IE8 features? You force the IE8 web control to use the IE8 mode by adding this to your game pages: <meta http-equiv="X-UA-Compatible" content="IE=edge" >

For more information, see the Microsoft reference on IE8 extensibility improvements and Microsoft reference on compatibility.

Sizing the Game Window

The Messenger Games Plug-in uses only the full canvas view, so your Gadget XML file should only use YahooFullView in the game window.

Whenever possible, YAP games should use flexible sizing, so the entire game window can flex to fit the available full canvas. This is because the full canvas view can vary slightly depending on whether the canvas appears in the Yahoo! home page, Yahoo! Pulse, the Messenger Games Plug-in, or some other location. (Hint: more are coming).

760 pixels wide by 600 pixels high is full canvas viewYMessengerGamesPluginCanvas

The Messenger Games Plug-in uses a full canvas that is 760 pixels wide and 600 pixels high. The width can't be greater than 760 px, but the height can be greater than 600 px. Note however that the user will have to either scroll or stretch the window manually in order to use more than 600 px of vertical canvas. Also note that, unlike Yahoo! Pulse, there is currently no YAP chrome at the top of the game window.

Linking Properly

If your game has a link or form that points back to the page itself (or a relative path based on YahooFullView), you need to use yml:a or yml:form, rather than standard HTML tags.

If you do not take this precaution, a link pointing to the same page or to a relative path will be redirected to the Yahoo! Pulse game page by YAP. To prevent showing this page in the Messenger game window, the new page will open in an external web browser. As you can imagine, this is not an optimal user experience. More details are available in:

* YML reference
* YML parameter encoding example

If your game page has a link pointing to an external page, like or, make sure to specify target="_blank" in your code. The plug-in will then open it in an external web browser.

If you don't do this, the page will be opened inside the game window, and the user will have no way to navigate back. We assume the game should have its own UI to let users navigate the game pages; if it's not a "game page," it should be opened in new window.

Debugging in Messenger Games Plug-in

First, make sure the game is working well in all IE browsers.

If the game works fine otherwise, but you encounter problems with the Games Plug-in, check all the script alert options in IE.

IE Internet Options dialog showing options unchecked for disabling script debugging and checked for displaying notificationsIE_Debugging

JavaScript errors will trigger the Games Plug-in to create an error dialog box, which you can then examine.

IE Webpage Error message with Use the Built-in Script Debugger checkedIE_script_error_message

If you need to identify HTTP problems, try Fiddler or a similar tool.

This post was co-authored by Chao Wang on our Engineering team.