rem: this.map.setCenter(this.map.center);  
add: if (this.performedDrag) { this.map.setCenter(this.map.center); } 
context:     defaultMouseUp: function (evt) {        if (!Event.isLeftClick(evt)) return;        switch (this.mode) {            case "zoombox":                var start = this.map.getLonLatFromViewPortPx( this.mouseDragStart );                 var end = this.map.getLonLatFromViewPortPx( evt.xy );                var top = Math.max(start.lat, end.lat);                var bottom = Math.min(start.lat, end.lat);                var left = Math.min(start.lon, end.lon);                var right = Math.max(start.lon, end.lon);                var bounds = new OpenLayers.Bounds(left, bottom, right, top);                var zoom = this.map.getZoomForExtent(bounds);                this.map.setCenter(new OpenLayers.LonLat(                  (start.lon + end.lon) / 2,                  (start.lat + end.lat) / 2                 ), zoom);                this.map.viewPortDiv.removeChild(document.getElementById("zoomBox"));                this.zoomBox = null;                this.leaveMode();                break;            case "pan":                this.map.setCenter(this.map.center);                    }        document.onselectstart = null;        this.mouseDragStart = null;        this.map.div.style.cursor = "default";    },
meta: 4411	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/4411/b4a3bfa9c21d9bad6ad6e0ff477f2acb3c72f08d/MouseToolbar.js/clean/lib/OpenLayers/Control/MouseToolbar.js