Index: wp-admin/js/revisions.js
===================================================================
--- wp-admin/js/revisions.js	(revision 24382)
+++ wp-admin/js/revisions.js	(working copy)
@@ -302,7 +302,7 @@
 				value: 0,
 				min: 0,
 				max: 1,
-				step: 1
+				animate: true // enables click to slide
 			});
 		},
 
@@ -344,6 +344,11 @@
 		 * also swaps in the appropriate models - left handled or right handled
 		 */
 		start: function( event, ui ) {
+			// track the mouse position to enable smooth dragging, overrides default jquery ui step behaviour
+			$( window ).mousemove( function( e ) {
+				$( ui.handle ).css( 'left', e.clientX - $( '#diff-slider' ).offset().left ); // subtract offset of container
+			});
+
 			// Not needed in one mode
 			if ( this.singleRevision )
 				return;
@@ -387,6 +392,20 @@
 		 * the other handle compares to this handle's position, so if it changes they need to be recalculated
 		 */
 		stop: function( event, ui ) {
+			$( window ).unbind( 'mousemove' ); // stop tracking the mouse
+			/**
+			 * pop the handle back to the step position by resetting the value(s)
+			 */
+			if ( Diff.slider.singleRevision ) {
+				Diff.slider.refresh({
+					value: Diff.rightDiff - 1
+				} );
+			} else {
+				Diff.slider.refresh( {
+					values: [ isRtl ? Diff.rightDiff : Diff.leftDiff, isRtl ? Diff.leftDiff : Diff.rightDiff ]
+				} );
+			}
+
 			// Not needed in one mode
 			if ( this.singleRevision )
 				return;