diff --git a/manifest.json b/manifest.json
index 4922bd8..4e32964 100644
--- a/manifest.json
+++ b/manifest.json
@@ -15,7 +15,8 @@
     ]
   },
   "permissions": [
-    "sessions"
+    "sessions",
+    "tabs"
   ],
   "web_accessible_resources": [
     "build/console.html"
diff --git a/src/background/commands.js b/src/background/commands.js
deleted file mode 100644
index 8bd52e5..0000000
--- a/src/background/commands.js
+++ /dev/null
@@ -1,2 +0,0 @@
-export const OPEN = 'open';
-export const TABOPEN = 'tabopen';
diff --git a/src/background/index.js b/src/background/index.js
index 7618384..15c8ab0 100644
--- a/src/background/index.js
+++ b/src/background/index.js
@@ -1,54 +1,50 @@
 import * as actions from '../shared/actions';
 import * as tabs from './tabs';
-import * as commands from './commands';
 import * as zooms from './zooms';
 import KeyQueue from './key-queue';
 
 const queue = new KeyQueue();
 
-const keyPressHandle = (request, sender, sendResponse) => {
+const keyPressHandle = (request, sender) => {
   let action = queue.push({
     code: request.code,
     ctrl: request.ctrl
   });
   if (!action) {
-    return;
+    return Promise.resolve();
   }
 
   if (actions.isBackgroundAction(action[0])) {
-    doBackgroundAction(sender, action);
+    return doBackgroundAction(sender, action);
   } else if (actions.isContentAction(action[0])) {
-    sendResponse(action);
+    return Promise.resolve({
+      type: 'response.action',
+      action: action
+    });
   }
+  return Promise.resolve();
 };
 
 const doBackgroundAction = (sender, action) => {
   switch(action[0]) {
   case actions.TABS_CLOSE:
-    tabs.closeTab(sender.tab.id);
-    break;
+    return tabs.closeTab(sender.tab.id);
   case actions.TABS_REOPEN:
-    tabs.reopenTab();
-    break;
+    return tabs.reopenTab();
   case actions.TABS_PREV:
-    tabs.selectPrevTab(sender.tab.index, actions[1] || 1);
-    break;
+    return tabs.selectPrevTab(sender.tab.index, actions[1] || 1);
   case actions.TABS_NEXT:
-    tabs.selectNextTab(sender.tab.index, actions[1] || 1);
-    break;
+    return tabs.selectNextTab(sender.tab.index, actions[1] || 1);
   case actions.TABS_RELOAD:
-    tabs.reload(sender.tab, actions[1] || false);
-    break;
+    return tabs.reload(sender.tab, actions[1] || false);
   case actions.ZOOM_IN:
-    zooms.zoomIn();
-    break;
+    return zooms.zoomIn();
   case actions.ZOOM_OUT:
-    zooms.zoomOut();
-    break;
+    return zooms.zoomOut();
   case actions.ZOOM_NEUTRAL:
-    zooms.neutral();
-    break;
+    return zooms.neutral();
   }
+  return Promise.resolve();
 }
 
 const normalizeUrl = (string) => {
@@ -59,28 +55,38 @@ const normalizeUrl = (string) => {
   }
 }
 
+const cmdBuffer = (arg) => {
+  if (isNaN(arg)) {
+    return tabs.selectByKeyword(arg);
+  } else {
+    let index = parseInt(arg, 10) - 1;
+    return tabs.selectAt(index);
+  }
+}
+
 const cmdEnterHandle = (request, sender) => {
   let words = request.text.split(' ').filter((s) => s.length > 0);
   switch (words[0]) {
-  case commands.OPEN:
-    browser.tabs.update(sender.tab.id, { url: normalizeUrl(words[1]) });
-    return;
-  case commands.TABOPEN:
-    browser.tabs.create({ url: normalizeUrl(words[1]) });
-    return;
+  case 'open':
+    return browser.tabs.update(sender.tab.id, { url: normalizeUrl(words[1]) });
+  case 'tabopen':
+    return browser.tabs.create({ url: normalizeUrl(words[1]) });
+  case 'b':
+  case 'buffer':
+    return cmdBuffer(words[1]);
   }
+  throw new Error(words[0] + ' command is not defined');
 };
 
-browser.runtime.onMessage.addListener((request, sender, sendResponse) => {
+browser.runtime.onMessage.addListener((request, sender) => {
   switch (request.type) {
   case 'event.keypress':
-    keyPressHandle(request, sender, sendResponse);
-    break;
+    return keyPressHandle(request, sender);
   case 'event.cmd.enter':
-    cmdEnterHandle(request, sender, sendResponse);
-    break;
+    return cmdEnterHandle(request, sender);
   case 'event.cmd.suggest':
-    // TODO make suggestion and return via sendResponse
+    // TODO make suggestion and return
     break;
   }
+  return Promise.resolve();
 });
diff --git a/src/background/key-queue.js b/src/background/key-queue.js
index 3805305..d7f0984 100644
--- a/src/background/key-queue.js
+++ b/src/background/key-queue.js
@@ -4,6 +4,7 @@ const DEFAULT_KEYMAP = {
   ':': [ actions.CMD_OPEN ],
   'o': [ actions.CMD_TABS_OPEN, false ],
   'O': [ actions.CMD_TABS_OPEN, true ],
+  'b': [ actions.CMD_BUFFER ],
   'k': [ actions.SCROLL_LINES, -1 ],
   'j': [ actions.SCROLL_LINES, 1 ],
   '<C-E>': [ actions.SCROLL_LINES, -1 ],
diff --git a/src/background/tabs.js b/src/background/tabs.js
index 56f86eb..efecdc4 100644
--- a/src/background/tabs.js
+++ b/src/background/tabs.js
@@ -1,9 +1,9 @@
 const closeTab = (id) => {
-  browser.tabs.remove(id);
+  return browser.tabs.remove(id);
 };
 
 const reopenTab = () => {
-  browser.sessions.getRecentlyClosed({
+  return browser.sessions.getRecentlyClosed({
     maxResults: 1
   }).then((sessions) => {
     if (sessions.length === 0) {
@@ -11,40 +11,69 @@ const reopenTab = () => {
     }
     let session = sessions[0];
     if (session.tab) {
-      browser.sessions.restore(session.tab.sessionId);
+      return browser.sessions.restore(session.tab.sessionId);
     } else {
-      browser.sessions.restore(session.window.sessionId);
+      return browser.sessions.restore(session.window.sessionId);
     }
   });
 };
 
+const selectAt = (index) => {
+  return browser.tabs.query({ currentWindow: true }, (tabs) => {
+    if (tabs.length < 2) {
+      return;
+    }
+    if (index < 0 || tabs.length <= index) {
+      throw new RangeError(`tab ${index} does not exist`)
+    }
+    let id = tabs[index].id;
+    return browser.tabs.update(id, { active: true })
+  });
+};
+
+const selectByKeyword = (keyword) => {
+  return browser.tabs.query({ currentWindow: true }).then((tabs) => {
+    let matched = tabs.filter((t) => {
+      return t.url.includes(keyword) || t.title.includes(keyword)
+    })
+
+    if (matched.length == 0) {
+      throw new RangeError('No matching buffer for ' + keyword);
+    } else if (matched.length >= 2) {
+      throw new RangeError('More than one match for ' + keyword);
+    }
+
+    return browser.tabs.update(matched[0].id, { active: true });
+  });
+}
+
 const selectPrevTab = (current, count) => {
-  chrome.tabs.query({ currentWindow: true }, (tabs) => {
+  return browser.tabs.query({ currentWindow: true }, (tabs) => {
     if (tabs.length < 2) {
       return;
     }
     let select = (current - count) % tabs.length
     let id = tabs[select].id;
-    chrome.tabs.update(id, { active: true })
+    return browser.tabs.update(id, { active: true })
   });
 };
 
 const selectNextTab = (current, count) => {
-  chrome.tabs.query({ currentWindow: true }, (tabs) => {
+  return browser.tabs.query({ currentWindow: true }, (tabs) => {
     if (tabs.length < 2) {
       return;
     }
     let select = (current + count + tabs.length) % tabs.length
     let id = tabs[select].id;
-    chrome.tabs.update(id, { active: true })
+    return browser.tabs.update(id, { active: true })
   });
 };
 
 const reload = (current, cache) => {
-  browser.tabs.reload(
+  return browser.tabs.reload(
     current.id,
     { bypassCache: cache }
   );
 };
 
-export { closeTab, reopenTab, selectNextTab, selectPrevTab, reload };
+export { closeTab, reopenTab, selectAt, selectByKeyword, selectNextTab, selectPrevTab, reload };
diff --git a/src/background/zooms.js b/src/background/zooms.js
index bb65030..e3e2aa6 100644
--- a/src/background/zooms.js
+++ b/src/background/zooms.js
@@ -10,7 +10,7 @@ const ZOOM_SETTINGS = [
 ];
 
 const zoomIn = (tabId = undefined) => {
-  browser.tabs.getZoom(tabId).then((factor) => {
+  return browser.tabs.getZoom(tabId).then((factor) => {
     for (let f of ZOOM_SETTINGS) {
       if (f > factor) {
         browser.tabs.setZoom(tabId, f);
@@ -21,7 +21,7 @@ const zoomIn = (tabId = undefined) => {
 };
 
 const zoomOut = (tabId = undefined) => {
-  browser.tabs.getZoom(tabId).then((factor) => {
+  return browser.tabs.getZoom(tabId).then((factor) => {
     for (let f of [].concat(ZOOM_SETTINGS).reverse()) {
       if (f < factor) {
         browser.tabs.setZoom(tabId, f);
@@ -32,7 +32,7 @@ const zoomOut = (tabId = undefined) => {
 };
 
 const neutral = (tabId = undefined) => {
-  browser.tabs.setZoom(tabId, 1);
+  return browser.tabs.setZoom(tabId, 1);
 };
 
 export { zoomIn, zoomOut, neutral };
diff --git a/src/console/console-frame.js b/src/console/console-frame.js
index aabb96a..ea9f523 100644
--- a/src/console/console-frame.js
+++ b/src/console/console-frame.js
@@ -10,6 +10,8 @@ export default class ConsoleFrame {
 
     this.element = element;
 
+    this.errorShown = true;
+
     this.hide();
   }
 
@@ -21,6 +23,7 @@ export default class ConsoleFrame {
       text: text
     };
     messages.send(this.element.contentWindow, message);
+    this.errorShown = false;
   }
 
   showError(text) {
@@ -31,6 +34,8 @@ export default class ConsoleFrame {
       text: text
     };
     messages.send(this.element.contentWindow, message);
+    this.errorShown = true;
+    this.element.blur();
   }
 
   showFrame() {
@@ -40,5 +45,10 @@ export default class ConsoleFrame {
   hide() {
     this.element.style.display = 'none';
     this.element.blur();
+    this.errorShown = false;
+  }
+
+  isErrorShown() {
+    return this.element.style.display === 'block' && this.errorShown;
   }
 }
diff --git a/src/console/console.js b/src/console/console.js
index a171ecc..e0227aa 100644
--- a/src/console/console.js
+++ b/src/console/console.js
@@ -8,20 +8,20 @@ var prevValue = "";
 
 const blurMessage = () => {
   return {
-    type: 'vimvixen.commandline.blur'
+    type: 'vimvixen.command.blur'
   };
 };
 
 const keydownMessage = (input) => {
   return {
-    type: 'vimvixen.commandline.enter',
+    type: 'vimvixen.command.enter',
     value: input.value
   };
 };
 
 const keyupMessage = (input) => {
   return {
-    type: 'vimvixen.commandline.change',
+    type: 'vimvixen.command.change',
     value: input.value
   };
 };
@@ -57,15 +57,15 @@ window.addEventListener('load', () => {
 });
 
 const showCommand = (text) => {
-  let input = window.document.querySelector('#vimvixen-console-command-input');
-  input.value = text;
-  input.focus();
-
   let command = window.document.querySelector('#vimvixen-console-command');
   command.style.display = 'block';
 
   let error = window.document.querySelector('#vimvixen-console-error');
   error.style.display = 'none';
+
+  let input = window.document.querySelector('#vimvixen-console-command-input');
+  input.value = text;
+  input.focus();
 }
 
 const showError = (text) => {
diff --git a/src/content/index.js b/src/content/index.js
index 66b1121..8b3eb58 100644
--- a/src/content/index.js
+++ b/src/content/index.js
@@ -7,7 +7,7 @@ import Follow from './follow';
 
 let vvConsole = new ConsoleFrame(window);
 
-const invokeEvent = (action) => {
+const doAction = (action) => {
   if (typeof action === 'undefined' || action === null) {
     return;
   }
@@ -24,6 +24,9 @@ const invokeEvent = (action) => {
       vvConsole.showCommand('open ');
     }
     break;
+  case actions.CMD_BUFFER:
+    vvConsole.showCommand('buffer ');
+    break;
   case actions.SCROLL_LINES:
     scrolls.scrollLines(window, action[1]);
     break;
@@ -54,6 +57,18 @@ const invokeEvent = (action) => {
   }
 }
 
+const handleResponse = (response) => {
+  if (!response) {
+    return;
+  }
+
+  switch(response.type) {
+  case 'response.action':
+    doAction(response.action);
+    break;
+  }
+};
+
 window.addEventListener("keypress", (e) => {
   if (e.target instanceof HTMLInputElement) {
     return;
@@ -66,27 +81,34 @@ window.addEventListener("keypress", (e) => {
   }
 
   browser.runtime.sendMessage(request)
-    .then(invokeEvent,
-      (err) => {
-        console.log(`Vim Vixen: ${err}`);
-      });
+    .then(handleResponse)
+    .catch((err) => {
+      vvConsole.showError(err.message);
+      console.log(`Vim Vixen: ${err}`);
+    });
 });
 
 messages.receive(window, (message) => {
   switch (message.type) {
-  case 'vimvixen.commandline.blur':
-    vvConsole.hide();
+  case 'vimvixen.command.blur':
+    if (!vvConsole.isErrorShown()) {
+      vvConsole.hide();
+    }
     break;
-  case 'vimvixen.commandline.enter':
+  case 'vimvixen.command.enter':
     browser.runtime.sendMessage({
       type: 'event.cmd.enter',
       text: message.value
+    }).catch((e) => {
+      vvConsole.showError(e.message);
     });
     break;
-  case 'vimvixen.commandline.change':
+  case 'vimvixen.command.change':
     browser.runtime.sendMessage({
       type: 'event.cmd.suggest',
       text: message.value
+    }).catch((e) => {
+      vvConsole.showError(e.message);
     });
     break;
   default:
diff --git a/src/shared/actions.js b/src/shared/actions.js
index cd740c2..7151dd1 100644
--- a/src/shared/actions.js
+++ b/src/shared/actions.js
@@ -1,5 +1,6 @@
 export const CMD_OPEN = 'cmd.open';
 export const CMD_TABS_OPEN = 'cmd.tabs.open';
+export const CMD_BUFFER = 'cmd.buffer';
 export const TABS_CLOSE = 'tabs.close';
 export const TABS_REOPEN = 'tabs.reopen';
 export const TABS_PREV = 'tabs.prev';
@@ -32,6 +33,7 @@ const BACKGROUND_ACTION_SET = new Set([
 const CONTENT_ACTION_SET = new Set([
   CMD_OPEN,
   CMD_TABS_OPEN,
+  CMD_BUFFER,
   SCROLL_LINES,
   SCROLL_PAGES,
   SCROLL_TOP,