--- a/mobile/chrome/content/aboutHome.xhtml
+++ b/mobile/chrome/content/aboutHome.xhtml
@@ -422,18 +422,20 @@
     }
 
     function uninitAddons() {
       getChromeWin().Services.obs.removeObserver(updateAddons, "recommended-addons-cache-updated");
     }
    
    function startDiscovery() {
      let win = getChromeWin();
+
+     // If a sidebar is completely open, just bail
      let [leftWidth, rightWidth] = win.Browser.computeSidebarVisibility();
-     if (leftWidth > 0 || rightWidth > 0) {
+     if (leftWidth == 1 || rightWidth == 1) {
        endDiscovery();
        return;
      }
 
      let doc = win.document;
      let broadcaster = doc.getElementById("bcast_uidiscovery");
 
      doc.addEventListener("animationend", endDiscovery, false);
@@ -446,17 +448,16 @@
      let broadcaster = doc.getElementById("bcast_uidiscovery");
 
      broadcaster.removeAttribute("mode");
      doc.removeEventListener("animationend", endDiscovery, false);
      doc.removeEventListener("PanBegin", endDiscovery, false);
    }
    
    function initLightbox() {
-
      let prefs = getChromeWin().Services.prefs;
      let channel = prefs.getCharPref("app.update.channel");
      let startupCount = 0;
      try {
        startupCount = prefs.getIntPref("app.promo.aurora");
        if(startupCount != 6)
          prefs.setIntPref("app.promo.aurora", ++startupCount);
      } catch(e) {

--- a/mobile/chrome/content/browser.js
+++ b/mobile/chrome/content/browser.js
@@ -273,18 +273,26 @@ var Browser = {
 
       // Tell the UI to resize the browser controls
       BrowserUI.sizeControls(w, h);
       ViewableAreaObserver.update();
 
       // Restore the previous scroll position
       let restorePosition = Browser.controlsPosition || { hideSidebars: true };
       if (restorePosition.hideSidebars) {
-        restorePosition.hideSidebars = false;
+        // Since this happens early in the startup process, we need to make sure
+        // the UI has really responded
+        let x = {}, y = {};
         Browser.hideSidebars();
+        Browser.controlsScrollboxScroller.getPosition(x, y);
+        if (x.value > 0) {
+          // Update the control position data so we are set correctly for the next resize
+          restorePosition.hideSidebars = false;
+          restorePosition.x = x.value;
+        }
       } else {
         // Handle Width transformation of the tabs sidebar
         if (restorePosition.x) {
           let [,, leftWidth, rightWidth] = Browser.computeSidebarVisibility();
           let delta = ((restorePosition.leftSidebar - leftWidth) || (restorePosition.rightSidebar - rightWidth));
           restorePosition.x += (restorePosition.x == leftWidth) ? delta : -delta;
         }