Index: wp-admin/css/colors-fresh.css
===================================================================
--- wp-admin/css/colors-fresh.css	(revision 24594)
+++ wp-admin/css/colors-fresh.css	(working copy)
@@ -1385,6 +1385,15 @@ table.diff .diff-addedline ins {
 	background-color: #fff;
 }
 
+
+.revisions-tickmarks {
+	background-color: #f7f7f7;
+}
+
+.revisions-tickmarks > div {
+	background-color: #ccc;
+}
+
 #diff-title-to strong {
 	color: #08a;
 }
@@ -1392,7 +1401,7 @@ table.diff .diff-addedline ins {
 /* jQuery UI Slider */
 .wp-slider.ui-slider {
 	border-color: #d7d7d7;
-	background: #f7f7f7;
+	background: transparent;
 }
 
 .wp-slider .ui-slider-handle {
Index: wp-admin/css/wp-admin.css
===================================================================
--- wp-admin/css/wp-admin.css	(revision 24594)
+++ wp-admin/css/wp-admin.css	(working copy)
@@ -3505,6 +3505,22 @@ td.plugin-title p {
 	height: 100px;
 }
 
+.revisions-tickmarks {
+	position: relative;
+	margin: 0 auto 0;
+	height: 0.8em;
+	z-index: 2;
+	top: 7px;
+}
+
+.revisions-tickmarks > div {
+	height: 0.8em;
+	width: 1px;
+	float: left;
+	position: relative;
+	z-index: 10002;
+}
+
 .comparing-two-revisions .revisions-controls {
 	height: 140px;
 }
@@ -3534,7 +3550,8 @@ td.plugin-title p {
 
 .wp-slider {
 	width: 70%;
-	margin: 6px auto 0;
+	margin: 0 auto 0;
+	top: -3px;
 }
 
 /* Revision meta box */
Index: wp-admin/js/revisions.js
===================================================================
--- wp-admin/js/revisions.js	(revision 24594)
+++ wp-admin/js/revisions.js	(working copy)
@@ -280,7 +280,10 @@ window.wp = window.wp || {};
 		},
 
 		updateCompareTwoMode: function() {
-			this.$el.toggleClass( 'comparing-two-revisions' );
+			if ( this.model.get( 'compareTwoMode' ) )
+				this.$el.addClass( 'comparing-two-revisions' );
+			else
+				this.$el.removeClass( 'comparing-two-revisions' );
 		}
 	});
 
@@ -307,6 +310,11 @@ window.wp = window.wp || {};
 			});
 			this.views.add( tooltip );
 
+			// Add the Tickmarks view
+			this.views.add( new revisions.view.Tickmarks({
+				model: this.model
+			}));
+
 			// Add the Slider view with a reference to the tooltip view
 			this.views.add( new revisions.view.Slider({
 				model: this.model,
@@ -317,6 +325,39 @@ window.wp = window.wp || {};
 			this.views.add( new revisions.view.Meta({
 				model: this.model
 			}) );
+
+		}
+	});
+
+	// The tickmarks view
+	// This contains the slider tickmarks.
+	revisions.view.Tickmarks = wp.Backbone.View.extend({
+		tagName: 'div',
+		className: 'revisions-tickmarks',
+		template: wp.template('revisions-tickmarks'),
+
+		numberOfTickmarksSet: function() {
+			var tickCount = this.model.revisions.length - 1, // One tickmark per model
+				sliderWidth = $( '.wp-slider' ).parent().width() * 0.7, // Width of slider is 70% of container (reset on resize)
+				tickWidth = Math.floor( sliderWidth / tickCount ), // Divide width by # of tickmarks, round down
+				newSiderWidth = ( ( tickWidth + 1 ) * tickCount ) + 1, // Calculate the actual width
+				tickNumber;
+
+			$( '.wp-slider' ).css( 'width', newSiderWidth ); // Reset the slider width to match the calculated tick size
+			this.$el.css( 'width', newSiderWidth ); // Match the tickmark div width
+
+			for ( tickNumber = 0; tickNumber <= tickCount; tickNumber++ ){
+				this.$el.append( '<div style="left:' + ( tickWidth * tickNumber ) + 'px;"></div>' );
+			}
+		},
+
+		ready: function() {
+			var self = this;
+			self.numberOfTickmarksSet();
+			$( window ).on( 'resize', _.debounce( function() {
+				self.$el.html( '' );
+				self.numberOfTickmarksSet();
+				}, 50 ) );
 		}
 	});
 
@@ -511,8 +552,8 @@ window.wp = window.wp || {};
 
 		events: {
 			'mousemove'  : 'mousemove',
-			'mouseenter' : 'mouseenter',
-			'mouseleave' : 'mouseleave'
+			'mouseleave' : 'mouseleave',
+			'mouseenter' : 'mouseenter'
 		},
 
 		initialize: function( options ) {
@@ -559,35 +600,37 @@ window.wp = window.wp || {};
 		},
 
 		mousemove: function( e ) {
-			var sliderLeft = Math.ceil( this.$el.offset().left ),
-				sliderWidth = Math.ceil( this.$el.width() ) + 2,
-				tickWidth = Math.ceil( ( sliderWidth ) / this.model.revisions.length ),
-				actualX = e.clientX - sliderLeft,
-				hoveringAt = Math.floor( actualX / tickWidth );
+			var tickCount = this.model.revisions.length - 1, // One tickmark per model
+				sliderLeft = Math.ceil( this.$el.offset().left ), // Left edge of slider
+				sliderWidth = this.$el.width(), // Width of slider
+				tickWidth = Math.floor( sliderWidth / tickCount ), // Calculated width of tickmark
+				actualX = e.clientX - sliderLeft, // Offset of mouse position in slider
+				currentModelIndex = Math.floor( ( actualX + tickWidth / 2 ) / tickWidth ), // Calculate the model index
+				tooltipPosition = sliderLeft + 2 + currentModelIndex * tickWidth; // Stick tooltip to tickmark
 
 			// Reverse direction in RTL mode.
 			if ( isRtl )
-				hoveringAt = this.model.revisions.length - hoveringAt - 1;
+				currentModelIndex = this.model.revisions.length - currentModelIndex - 1;
 
-			// Ensure sane value for hoveringAt.
-			if ( hoveringAt < 0 )
-				hoveringAt = 0;
-			else if ( hoveringAt >= this.model.revisions.length )
-				hoveringAt = this.model.revisions.length - 1;
+			// Ensure sane value for currentModelIndex.
+			if ( currentModelIndex < 0 )
+				currentModelIndex = 0;
+			else if ( currentModelIndex >= this.model.revisions.length )
+				currentModelIndex = this.model.revisions.length - 1;
 
 			// Update the tooltip model
-			this.tooltip.model.set( 'revision', this.model.revisions.at( hoveringAt ) );
-			this.tooltip.model.set( 'position', e.clientX );
-		},
-
-		mouseenter: function( e ) {
-			this.tooltip.show();
+			this.tooltip.model.set( 'revision', this.model.revisions.at( currentModelIndex ) );
+			this.tooltip.model.set( 'position', tooltipPosition );
 		},
 
 		mouseleave: function( e ) {
 			this.tooltip.hide();
 		},
 
+		mouseenter: function( e ) {
+			this.tooltip.show();
+		},
+
 		updateSliderSettings: function() {
 			if ( this.model.get( 'compareTwoMode' ) ) {
 				var leftValue, rightValue;
Index: wp-admin/revision.php
===================================================================
--- wp-admin/revision.php	(revision 24594)
+++ wp-admin/revision.php	(working copy)
@@ -152,6 +152,9 @@ require_once( './admin-header.php' );
 	</div>
 </script>
 
+<script id="tmpl-revisions-tickmarks" type="text/html">
+</script>
+
 <script id="tmpl-revisions-meta" type="text/html">
 	<div id="diff-header">
 		<div id="diff-header-from" class="diff-header">
