--- a/layout/xul/nsDeckFrame.cpp
+++ b/layout/xul/nsDeckFrame.cpp
@@ -105,16 +105,23 @@ nsDeckFrame::IndexChanged()
 
 #ifdef ACCESSIBILITY
   nsAccessibilityService* accService = GetAccService();
   if (accService) {
     accService->DeckPanelSwitched(PresContext()->GetPresShell(), mContent,
                                   currentBox, GetSelectedBox());
   }
 #endif
+
+  // Force any popups that might be anchored on elements within hidden
+  // box to update.
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && currentBox) {
+    pm->UpdatePopupPositions(currentBox->PresContext()->RefreshDriver());
+  }
 }
 
 int32_t
 nsDeckFrame::GetSelectedIndex()
 {
   // default index is 0
   int32_t index = 0;