diff -r 000000000000 -r 6474c204b198 browser/base/content/test/newtab/browser_newtab_bug752841.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/newtab/browser_newtab_bug752841.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const PREF_NEWTAB_ROWS = "browser.newtabpage.rows";
+const PREF_NEWTAB_COLUMNS = "browser.newtabpage.columns";
+
+function runTests() {
+  let testValues = [
+    {row: 0, column: 0},
+    {row: -1, column: -1},
+    {row: -1, column: 0},
+    {row: 0, column: -1},
+    {row: 2, column: 4},
+    {row: 2, column: 5},
+  ];
+
+  // Expected length of grid
+  let expectedValues = [1, 1, 1, 1, 8, 10];
+
+   // Values before setting new pref values (9 is the default value -> 3 x 3)
+  let previousValues = [9, 1, 1, 1, 1, 8];
+
+  let existingTab, existingTabGridLength, newTab, newTabGridLength;
+  yield addNewTabPageTab();
+  existingTab = gBrowser.selectedTab;
+
+  for (let i = 0; i < expectedValues.length; i++) {
+    gBrowser.selectedTab = existingTab;
+    existingTabGridLength = getGrid().cells.length;
+    is(existingTabGridLength, previousValues[i],
+      "Grid length of existing page before update is correctly.");
+
+    Services.prefs.setIntPref(PREF_NEWTAB_ROWS, testValues[i].row);
+    Services.prefs.setIntPref(PREF_NEWTAB_COLUMNS, testValues[i].column);
+
+    existingTabGridLength = getGrid().cells.length;
+    is(existingTabGridLength, expectedValues[i],
+      "Existing page grid is updated correctly.");
+
+    yield addNewTabPageTab();
+    newTab = gBrowser.selectedTab;
+    newTabGridLength = getGrid().cells.length;
+    is(newTabGridLength, expectedValues[i],
+      "New page grid is updated correctly.");
+
+    gBrowser.removeTab(newTab);
+  }
+
+  gBrowser.removeTab(existingTab);
+
+  Services.prefs.clearUserPref(PREF_NEWTAB_ROWS);
+  Services.prefs.clearUserPref(PREF_NEWTAB_COLUMNS);
+}