diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 0b7f8791c7a..5407bcbd38d 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -3505,19 +3505,13 @@ function BrowserCustomizeToolbar()
   gCustomizeSheet = getBoolPref("toolbar.customization.usesheet", false);
 
   if (gCustomizeSheet) {
-    var sheetFrame = document.getElementById("customizeToolbarSheetIFrame");
-    var panel = document.getElementById("customizeToolbarSheetPopup");
-    sheetFrame.hidden = false;
+    let sheetFrame = document.createElement("iframe");
+    let panel = document.getElementById("customizeToolbarSheetPopup");
+    sheetFrame.id = "customizeToolbarSheetIFrame";
     sheetFrame.toolbox = gNavToolbox;
     sheetFrame.panel = panel;
-
-    // The document might not have been loaded yet, if this is the first time.
-    // If it is already loaded, reload it so that the onload initialization code
-    // re-runs.
-    if (sheetFrame.getAttribute("src") == customizeURL)
-      sheetFrame.contentWindow.location.reload()
-    else
-      sheetFrame.setAttribute("src", customizeURL);
+    sheetFrame.setAttribute("style", panel.getAttribute("sheetstyle"));
+    panel.appendChild(sheetFrame);
 
     // Open the panel, but make it invisible until the iframe has loaded so
     // that the user doesn't see a white flash.
@@ -3526,6 +3520,9 @@ function BrowserCustomizeToolbar()
       gNavToolbox.removeEventListener("beforecustomization", onBeforeCustomization, false);
       panel.style.removeProperty("visibility");
     }, false);
+
+    sheetFrame.setAttribute("src", customizeURL);
+
     panel.openPopup(gNavToolbox, "after_start", 0, 0);
     return sheetFrame.contentWindow;
   } else {
@@ -3538,8 +3535,9 @@ function BrowserCustomizeToolbar()
 
 function BrowserToolboxCustomizeDone(aToolboxChanged) {
   if (gCustomizeSheet) {
-    document.getElementById("customizeToolbarSheetIFrame").hidden = true;
     document.getElementById("customizeToolbarSheetPopup").hidePopup();
+    let iframe = document.getElementById("customizeToolbarSheetIFrame");
+    iframe.parentNode.removeChild(iframe);
   }
 
   // Update global UI elements that may have been added or removed
diff --git a/browser/base/content/browser.xul b/browser/base/content/browser.xul
index 4308c176fea..d27269677ce 100644
--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -344,11 +344,8 @@
     <tooltip id="bhTooltip"/>
 
     <panel id="customizeToolbarSheetPopup"
-           noautohide="true">
-      <iframe id="customizeToolbarSheetIFrame"
-              style="&dialog.dimensions;"
-              hidden="true"/>
-    </panel>
+           noautohide="true"
+           sheetstyle="&dialog.dimensions;"/>
 
     <tooltip id="tabbrowser-tab-tooltip" onpopupshowing="gBrowser.createTooltip(event);"/>