Address @ellisonbg's comments

notebook/static/notebook/js/actions.js

@@ -423,12 +423,12 @@ define(function(require){
                 env.notebook.show_command_palette();
             }
         },
-        'toggle-marks': {
+        'toggle-cell-marked': {
             help_index : 'cj',
             help: 'toggle marks',
             icon: 'fa-check',
             handler : function(env){
-                env.notebook.toggle_marks(env.notebook.get_selected_cells());
+                env.notebook.toggle_cells_marked(env.notebook.get_selected_cells());
             }
         },
     };

notebook/static/notebook/js/keyboardmanager.js

@@ -93,7 +93,7 @@ define([
             'enter' : 'ipython.enter-edit-mode',
             'space' : 'ipython.scroll-down',
             'down' : 'ipython.select-next-cell',
-            'ctrl-space' : 'ipython.toggle-marks',
+            'ctrl-space' : 'ipython.toggle-cell-marked',
             'i,i' : 'ipython.interrupt-kernel',
             '0,0' : 'ipython.restart-kernel',
             'd,d' : 'ipython.delete-cell',

notebook/static/notebook/js/notebook.js

@@ -401,7 +401,7 @@ define(function (require) {
         var st = sme.scrollTop();
         var t = sme.offset().top;
         var ct = cells[index].element.offset().top;
-        var scroll_value =  st + ct - (t + .01 * percent * h);
+        var scroll_value =  st + ct - (t + 0.01 * percent * h);
         this.scroll_manager.element.animate({scrollTop:scroll_value}, time);
         return scroll_value;
     };
@@ -633,7 +633,7 @@ define(function (require) {
      * Toggles the marks on the cells
      * @param  {Cell[]} [cells] - optionally specify what cells should be toggled
      */
-    Notebook.prototype.toggle_marks = function(cells) {
+    Notebook.prototype.toggle_cells_marked = function(cells) {
         cells = cells || this.get_cells();
         cells.forEach(function(cell) { cell.marked = !cell.marked; });
     };
@@ -642,7 +642,7 @@ define(function (require) {
      * Mark all of the cells
      * @param  {Cell[]} [cells] - optionally specify what cells should be marked
      */
-    Notebook.prototype.mark_all = function(cells) {
+    Notebook.prototype.mark_all_cells = function(cells) {
         cells = cells || this.get_cells();
         cells.forEach(function(cell) { cell.mark(); });
     };
@@ -651,7 +651,7 @@ define(function (require) {
      * Unmark all of the cells
      * @param  {Cell[]} [cells] - optionally specify what cells should be unmarked
      */
-    Notebook.prototype.unmark_all = function(cells) {
+    Notebook.prototype.unmark_all_cells = function(cells) {
         this.get_marked_cells(cells).forEach(function(cell) { cell.unmark(); });
     };
     
@@ -660,8 +660,8 @@ define(function (require) {
      * @param  {Cell[]} cells
      */
     Notebook.prototype.set_marked_cells = function(cells) {
-        this.unmark_all();
-        this.mark_all(cells);
+        this.unmark_all_cells();
+        this.mark_all_cells(cells);
     };
     
     /**
@@ -681,8 +681,8 @@ define(function (require) {
      */
     Notebook.prototype.set_marked_indices = function(indices, cells) {
         cells = cells || this.get_cells();
-        this.unmark_all(cells);
-        this.mark_all(cells.filter(function(cell, index) { return indices.indexOf(index) !== -1; }));
+        this.unmark_all_cells(cells);
+        this.mark_all_cells(cells.filter(function(cell, index) { return indices.indexOf(index) !== -1; }));
     };
     
     /**
@@ -695,6 +695,25 @@ define(function (require) {
         var markedCells = this.get_marked_cells(cells);
         return markedCells.map(function(cell) { return cells.indexOf(cell); });
     };
+    
+    /**
+     * Checks if the marked cells are contiguous
+     * @param  {Cell[]} [cells] - optionally provide the cells to search through
+     * @return {boolean}
+     */
+    Notebook.prototype.are_marks_contiguous = function(cells) {
+        // Get a numerically sorted list of the marked indices.
+        var markedIndices = this.get_marked_indices(cells).sort(
+            function(a,b) { return a-b; });
+
+        // Check for contiguousness
+        for (var i = 0; i < markedIndices.length - 1; i++) {
+            if (markedIndices[i+1] - markedIndices[i] !== 1) {
+                return false;
+            }
+        }
+        return true;
+    };
 
     /**
      * Get an array of the cells in the currently selected range

notebook/static/notebook/less/cell.less

@@ -25,6 +25,7 @@ div.cell {
     &.marked {
         border-left-color: blue;
         border-left-width: 3px;
+        margin-left: -2px;
     }
 
     width: 100%;

notebook/tests/notebook/marks.js

@@ -22,7 +22,7 @@ casper.notebook_test(function () {
         }), 0, 'no cells are marked visibily');
         
         this.evaluate(function() {
-            Jupyter.notebook.mark_all();
+            Jupyter.notebook.mark_all_cells();
         });
         
         var cellCount = this.evaluate(function() { 
@@ -38,7 +38,7 @@ casper.notebook_test(function () {
         }), cellCount, 'marked cells are marked visibily');
         
         this.evaluate(function() {
-            Jupyter.notebook.unmark_all();
+            Jupyter.notebook.unmark_all_cells();
         });
         
         this.test.assertEquals(this.evaluate(function() {