code: function(){
          if (this.map) {
              var getSlideFactor = OpenLayers.Function.bind(function (dim) {
                  return this.slideRatio ?
                      this.map.getSize()[dim] * this.slideRatio :
                      this.slideFactor;
              }, this);
      
              switch (this.direction) {
                  case OpenLayers.Control.Pan.NORTH: 
                      this.map.pan(0, -getSlideFactor("h"));
                      break;
                  case OpenLayers.Control.Pan.SOUTH: 
                      this.map.pan(0, getSlideFactor("h"));
                      break;
                  case OpenLayers.Control.Pan.WEST: 
                      this.map.pan(-getSlideFactor("w"), 0);
                      break;
                  case OpenLayers.Control.Pan.EAST: 
                      this.map.pan(getSlideFactor("w"), 0);
                      break;
              }   
          }
      }
docs: Method: trigger