[Proposal] skinning platform, agent, and language features

[Jeanne Waldman]

Hi there,

I would like to add some new features to the skinning portion of 
Trinidad, and I wanted to make sure no one had any concerns.

Basically, I'd like to allow the skinning person to define styles that 
are specific to a platform, an agent, and/or a language. Today in 
Trinidad, the user can create a different skin for each combination, and 
write skin-switching logic to switch between the skins depending upon 
the platform, the agent, and the language the request is coming from. I 
think that could get complicated, and seems hard to maintain.

I am proposing that we create skinning syntax for specifying styles for 
a specific platform, agent, and/or language.  The syntax for platform 
and agent will follow css2's @media syntax, and the syntax for the 
language support will use css2's existing :lang() pseudo-class (but 
we'll parse it into our internal data-structure).

Here is an example of using @platform and @agent:

/* if platforms is windows or ppc and if the agent is ie, then use ie's 
hand cursor for the column's sortable header text
*/
@platform windows, ppc {
 @agent ie {
   af|column::sortable-header-text {
     cursor: hand;
   }
 }
}


Here is an example of using the :lang pseudo-class.
/* change the default font family when the language is ja or zh-TW */
.AFDefaultFontFamily:alias:lang(ja),
.AFDefaultFontFamily:alias:lang(zh-TW) {
 font-family:Albany WTJ, Dialog;
}

The @agent feature is particularly useful if the skinning person is 
creating components that use ie-specific or gecko-specific css styles. 
They can use @agent ie {} for the ie-specific styling and @agent gecko 
{} for the gecko-specific styling, and when Trinidad parses the skinning 
css file and creates the css2 file that the page links to, it will only 
add the style selectors/properties for the particular 
platform/agent/language. Note that the css2 file that we generate from 
the skinning css file is specific to the end user's platform/agent/language.

Let me know if you have any questions, comments, or concerns. I'll open 
an issue and start implementing it if no one has any major concerns.

Thanks!
Jeanne