StyleSheet extension.js

       // Note that _disabledRules is also added to constructor.
       // These are the public API methods.


        /**
         * Enable a particular rule (or several) that's previously been disabled.
         * The selector parameter can be a RegExp; each rule matching the pattern
         * will be enabled
         * @param sel {String} String or RegExp to match to selectors to enable
         * @method enableRule
         * @return {StyleSheet} the StyleSheet instance
         * @chainable
         */
        enableRule : function (sel) {
        
          var i,
              disabled = _disabledRules,
              toEnable = [],
              thisToEnable,
              idx;
          
          for (i in disabled) {
          
            if (YAHOO.util.Lang.isString(i) && i.match(sel) !== null) {

              toEnable.push(i);
            }
          
          }

          for (i=0; i<toEnable.length; i++) {

              idx = sheet[_rules].length;
              thisToEnable = disabled[toEnable[i]];
              // Re-attach important declaration: Opera seems to lose it.
              if (thisToEnable.important && !thisToEnable.css.match("!important")) {
                
                thisToEnable.css += " !important";
                alert("is important " + thisToEnable.css)
              }
              this.set(thisToEnable.selectorText,thisToEnable.css);
              cssRules[i] = disabled[toEnable[i]];
              delete disabled[toEnable[i]];
            
          }

          return this;
        
        },


        /**
         * Disable a particular rule (or several) that's currently in the Sheet.
         * The selector parameter can be a RegExp; each rule matching the pattern
         * will be disabled
         * @param sel {String} String or RegExp to match to selectors to disable
         * @method disableRule
         * @return {StyleSheet} the StyleSheet instance
         * @chainable
         */        
        disableRule : function (sel) {

          var i, j = 0,
              enabled = cssRules,
              toDisable = [],
              idx;
          
          for (i in enabled) {

            if (YAHOO.util.Lang.isString(i) && i.match(sel) !== null && enabled[i].style.cssText) {

              toDisable.push(i);
              _disabledRules[i] = { css: enabled[i].style.cssText,
                                    important: enabled[i].style.cssText.match("!important"),
                                    selectorText: enabled[i].selectorText};
            }
            j++;
          }
      
          for (i=0; i<toDisable.length; i++) {

             this.unset(toDisable[i]);
             delete enabled[toDisable[i]];

          }
        
          return this;
        
        }