beep if trying to delete the last tab which is already an empty tab

content/events.js

@@ -661,8 +661,10 @@ function Events() //{{{
             vimperator.input.pendingArgMap = null;
             vimperator.input.pendingMotionMap = null;
 
-            stop = false; // command was not a vimperator command, maybe it is a firefox command
+            // allow key to be passed to firefox if we can't handle it
+            stop = false;
 
+            // TODO: see if this check is needed or are all motion commands already mapped in these modes?
             if (!vimperator.hasMode(vimperator.modes.COMMAND_LINE))
                 vimperator.beep();
         }

content/tabs.js

@@ -156,10 +156,16 @@ function Tabs() //{{{
             if (getBrowser().mTabs.length > 1)
                 getBrowser().removeTab(tab);
             else
+            {
+                if (vimperator.buffer.URL != "about:blank" ||
+                    getWebNavigation().sessionHistory.count > 0)
                 {
                     vimperator.open("about:blank", vimperator.NEW_BACKGROUND_TAB);
                     getBrowser().removeTab(tab);
                 }
+                else
+                    vimperator.beep();
+            }
         }
 
         if (count < 1)