diff --git a/examples/widgets/main.js b/examples/widgets/main.js
index a14ae7ec0b..2f81875af6 100644
--- a/examples/widgets/main.js
+++ b/examples/widgets/main.js
@@ -78,5 +78,5 @@ $(function () {
   });
 
   // Create a zoom slider widget
-  ui.createWidget('slider');
+  ui.createWidget('slider', {position: {left: 40, top: 40}});
 });
diff --git a/src/ui/sliderWidget.js b/src/ui/sliderWidget.js
index 977780674b..f86ff8794d 100644
--- a/src/ui/sliderWidget.js
+++ b/src/ui/sliderWidget.js
@@ -30,9 +30,9 @@ var sliderWidget = function (arg) {
       m_plus,
       m_minus,
       m_nub,
-      m_width = 20, // Approximate size of the widget in pixels
-      m_height = 100,
-      m_nubSize = 10,
+      m_width = arg.width || 20, // Size of the widget in pixels
+      m_height = arg.height || 160,  // slider height + 3 * width
+      m_nubSize = arg.width ? arg.width * 0.5 : 10,
       m_plusIcon,
       m_minusIcon,
       m_group,
@@ -83,6 +83,10 @@ var sliderWidget = function (arg) {
     return g;
   }
 
+  this.size = function () {
+    return {width: m_width, height: m_height};
+  };
+
   //////////////////////////////////////////////////////////////////////////////
   /**
    * Initialize the slider widget in the map.
@@ -99,14 +103,14 @@ var sliderWidget = function (arg) {
     m_this.reposition();
 
     var svg = d3.select(m_this.canvas()),
-        x0 = 40,
-        y0 = 40 + m_width,
         map = m_this.layer().map();
 
+    svg.attr('width', m_width).attr('height', m_height);
+
     // create d3 scales for positioning
     // TODO: make customizable and responsive
-    m_xscale = d3.scale.linear().domain([-4, 4]).range([x0, x0 + m_width]);
-    m_yscale = d3.scale.linear().domain([0, 1]).range([y0, y0 + m_height]);
+    m_xscale = d3.scale.linear().domain([-4, 4]).range([0, m_width]);
+    m_yscale = d3.scale.linear().domain([0, 1]).range([m_width * 1.5, m_height - m_width * 1.5]);
 
     // Create the main group element
     svg = svg.append('g').classed('geo-ui-slider', true);
@@ -122,7 +126,7 @@ var sliderWidget = function (arg) {
       .classed('geo-zoom-in', true)
       .attr('cx', m_xscale(0))
       .attr('cy', m_yscale(0.0) - m_width + 2)
-      .attr('r', m_width / 2)
+      .attr('r', (m_width - 2) / 2)
       .style({
         'cursor': 'pointer'
       })
@@ -143,7 +147,7 @@ var sliderWidget = function (arg) {
       m_plus,
       m_xscale(0),
       m_yscale(0) - m_width + 2,
-      m_width + 5
+      m_width + 4
     ).style('cursor', 'pointer')
       .style('pointer-events', 'none')
       .select('path')
@@ -162,7 +166,7 @@ var sliderWidget = function (arg) {
       .classed('geo-zoom-out', true)
       .attr('cx', m_xscale(0))
       .attr('cy', m_yscale(1.0) + m_width - 2)
-      .attr('r', m_width / 2)
+      .attr('r', (m_width - 2) / 2)
       .style({
         'cursor': 'pointer'
       })
@@ -183,7 +187,7 @@ var sliderWidget = function (arg) {
       m_minus,
       m_xscale(0),
       m_yscale(1) + m_width - 2,
-      m_width + 5
+      m_width + 4
     ).style('cursor', 'pointer')
       .style('pointer-events', 'none')
       .select('path')
@@ -194,7 +198,7 @@ var sliderWidget = function (arg) {
 
     // Respond to a mouse event on the widget
     function respond(evt, trans) {
-      var z = m_yscale.invert(d3.mouse(m_this.layer().node()[0])[1]),
+      var z = m_yscale.invert(d3.mouse(svg.node())[1]),
           zrange = map.zoomRange();
       z = (1 - z) * (zrange.max - zrange.min) + zrange.min;
       if (trans) {
@@ -223,7 +227,7 @@ var sliderWidget = function (arg) {
       .attr('rx', m_width / 10)
       .attr('ry', m_width / 10)
       .attr('width', m_width / 3)
-      .attr('height', m_height)
+      .attr('height', m_height - m_width * 3)
       .style({
         'cursor': 'pointer'
       })
diff --git a/src/ui/svgWidget.js b/src/ui/svgWidget.js
index 435e7d7391..a10a02ac5b 100644
--- a/src/ui/svgWidget.js
+++ b/src/ui/svgWidget.js
@@ -70,6 +70,9 @@ var svgWidget = function (arg) {
 
     m_renderer = d3Renderer(rendererOpts);
 
+    // svg widgets manage their own sizes, so make the resize handler a no-op
+    m_renderer._resize = function () {};
+
     m_this.canvas(m_renderer.canvas()[0][0]);
   };
 
diff --git a/src/ui/widget.js b/src/ui/widget.js
index 802ae6a495..0859c4fa5b 100644
--- a/src/ui/widget.js
+++ b/src/ui/widget.js
@@ -151,7 +151,9 @@ var widget = function (arg) {
 
       return {
         left: position.x,
-        top: position.y
+        top: position.y,
+        right: null,
+        bottom: null
       };
     }
 
@@ -172,7 +174,14 @@ var widget = function (arg) {
 
     for (var cssAttr in position) {
       if (position.hasOwnProperty(cssAttr)) {
-        m_this.canvas().style[cssAttr] = position[cssAttr] + 'px';
+        // if the property is a number, add px to it, otherwise set it to the
+        // specified value.  Setting a property to null clears it.  Setting to
+        // undefined doesn't alter it.
+        if (/^\s*(\-|\+)?(\d+(\.\d*)?|\d*\.\d+)([eE](\-|\+)?\d+)?\s*$/.test(position[cssAttr])) {
+          m_this.canvas().style[cssAttr] = ('' + position[cssAttr]).trim() + 'px';
+        } else {
+          m_this.canvas().style[cssAttr] = position[cssAttr];
+        }
       }
     }
   };
diff --git a/tests/cases/widgetApi.js b/tests/cases/widgetApi.js
index 2d3228636c..e059a4833d 100644
--- a/tests/cases/widgetApi.js
+++ b/tests/cases/widgetApi.js
@@ -79,6 +79,16 @@ describe('widget api', function () {
     expect($(widget.canvas()).position()).toEqual({top: 0, left: 0});
   });
 
+  it('Widgets positions can be changed', function () {
+    var o = makeMap(), widget = o.uiLayer.createWidget('dom', {
+          position: {left: 15, top: 10}});
+
+    expect($(widget.canvas()).position()).toEqual({top: 10, left: 15});
+    widget.position({top: null, bottom: '20%', left: 10});
+    expect(widget.position()).toEqual({top: null, bottom: '20%', left: 10});
+    expect($(widget.canvas()).position()).toEqual({top: 320, left: 10});
+  });
+
   it('nested widgets should be properly structured', function () {
     var o = makeMap();
     var domWidget = o.uiLayer.createWidget('dom');