diff --git a/qutebrowser/browser/hints.py b/qutebrowser/browser/hints.py
index 6fe13c7b0..d30e89aee 100644
--- a/qutebrowser/browser/hints.py
+++ b/qutebrowser/browser/hints.py
@@ -493,7 +493,9 @@ class HintManager(QObject):
         for e, string in zip(elems, strings):
             label = self._draw_label(e, string)
             self._context.elems[string] = ElemTuple(e, label)
-        keyparser = objreg.get('keyparsers')[usertypes.KeyMode.hint]
+        keyparsers = objreg.get('keyparsers', scope='window',
+                                window=self._win_id)
+        keyparser = keyparsers[usertypes.KeyMode.hint]
         keyparser.update_bindings(strings)
 
     def follow_prevnext(self, frame, baseurl, prev=False, newtab=False):
@@ -515,7 +517,9 @@ class HintManager(QObject):
                 "prev" if prev else "forward"))
         qtutils.ensure_valid(url)
         if newtab:
-            objreg.get('tabbed-browser').tabopen(url, background=False)
+            tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                        window=self._win_id)
+            tabbed_browser.tabopen(url, background=False)
         else:
             objreg.get('webview', scope='tab').openurl(url)
 
@@ -556,7 +560,8 @@ class HintManager(QObject):
                                 `{hint-url}` will get replaced by the selected
                                 URL.
         """
-        tabbed_browser = objreg.get('tabbed-browser')
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window=self._win_id)
         widget = tabbed_browser.currentWidget()
         if widget is None:
             raise cmdexc.CommandError("No WebView available yet!")
@@ -570,7 +575,9 @@ class HintManager(QObject):
         self._context.frames = webelem.get_child_frames(mainframe)
         self._context.args = args
         self._init_elements(mainframe, group)
-        objreg.get('message-bridge').set_text(self.HINT_TEXTS[target])
+        message_bridge = objreg.get('message-bridge', scope='window',
+                                    window=self._win_id)
+        message_bridge.set_text(self.HINT_TEXTS[target])
         self._connect_frame_signals()
         try:
             modeman.enter(self._win_id, usertypes.KeyMode.hint,
diff --git a/qutebrowser/browser/webpage.py b/qutebrowser/browser/webpage.py
index 5d06ec05e..09571a51f 100644
--- a/qutebrowser/browser/webpage.py
+++ b/qutebrowser/browser/webpage.py
@@ -300,11 +300,13 @@ class BrowserPage(QWebPage):
                 urlstr))
             log.webview.debug(url.errorString())
             return False
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window=self._win_id)
         if self.view().open_target == usertypes.ClickTarget.tab:
-            objreg.get('tabbed-browser').tabopen(url, False)
+            tabbed_browser.tabopen(url, False)
             return False
         elif self.view().open_target == usertypes.ClickTarget.tab_bg:
-            objreg.get('tabbed-browser').tabopen(url, True)
+            tabbed_browser.tabopen(url, True)
             return False
         else:
             return True
diff --git a/qutebrowser/commands/argparser.py b/qutebrowser/commands/argparser.py
index f2493825e..684361698 100644
--- a/qutebrowser/commands/argparser.py
+++ b/qutebrowser/commands/argparser.py
@@ -58,7 +58,9 @@ class HelpAction(argparse.Action):
     """
 
     def __call__(self, parser, _namespace, _values, _option_string=None):
-        objreg.get('tabbed-browser').tabopen(
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window='current')
+        tabbed_browser.tabopen(
             QUrl('qute://help/commands.html#{}'.format(parser.name)))
         parser.exit()
 
diff --git a/qutebrowser/commands/runners.py b/qutebrowser/commands/runners.py
index 9b89d8805..ccb859163 100644
--- a/qutebrowser/commands/runners.py
+++ b/qutebrowser/commands/runners.py
@@ -27,13 +27,15 @@ from qutebrowser.commands import cmdexc, cmdutils
 from qutebrowser.utils import message, log, utils, objreg
 
 
-def replace_variables(arglist):
+def replace_variables(win_id, arglist):
     """Utility function to replace variables like {url} in a list of args."""
     args = []
+    tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                window=win_id)
+    url = tabbed_browser.current_url().toString(QUrl.FullyEncoded |
+                                                QUrl.RemovePassword)
     for arg in arglist:
         if arg == '{url}':
-            url = objreg.get('tabbed-browser').current_url().toString(
-                QUrl.FullyEncoded | QUrl.RemovePassword)
             args.append(url)
         else:
             args.append(arg)
@@ -280,7 +282,7 @@ class CommandRunner:
                 self.run(sub, count)
             return
         self.parse(text)
-        args = replace_variables(self._args)
+        args = replace_variables(self._win_id, self._args)
         if count is not None:
             self._cmd.run(self._win_id, args, count=count)
         else:
diff --git a/qutebrowser/widgets/completion.py b/qutebrowser/widgets/completion.py
index 34c9418a6..f8379147d 100644
--- a/qutebrowser/widgets/completion.py
+++ b/qutebrowser/widgets/completion.py
@@ -46,6 +46,7 @@ class CompletionView(QTreeView):
 
     Attributes:
         enabled: Whether showing the CompletionView is enabled.
+        _win_id: The ID of the window this CompletionView is associated with.
         _height: The height to use for the CompletionView.
         _height_perc: Either None or a percentage if height should be relative.
         _delegate: The item delegate used.
@@ -91,6 +92,7 @@ class CompletionView(QTreeView):
 
     def __init__(self, win_id, parent=None):
         super().__init__(parent)
+        self._win_id = win_id
         objreg.register('completion', self, scope='window', window=win_id)
         completer_obj = completer.Completer(win_id)
         objreg.register('completer', completer_obj, scope='window',
@@ -226,7 +228,9 @@ class CompletionView(QTreeView):
     def selectionChanged(self, selected, deselected):
         """Extend selectionChanged to call completers selection_changed."""
         super().selectionChanged(selected, deselected)
-        objreg.get('completer').selection_changed(selected, deselected)
+        completer = objreg.get('completer', scope='window',
+                               window=self._win_id)
+        completer.selection_changed(selected, deselected)
 
     def resizeEvent(self, e):
         """Extend resizeEvent to adjust column size."""
diff --git a/qutebrowser/widgets/statusbar/prompter.py b/qutebrowser/widgets/statusbar/prompter.py
index 2fcc632fe..6b77ccc81 100644
--- a/qutebrowser/widgets/statusbar/prompter.py
+++ b/qutebrowser/widgets/statusbar/prompter.py
@@ -292,7 +292,8 @@ class Prompter:
         mode = self._display_question()
         question.aborted.connect(
             lambda: modeman.maybe_leave(self._win_id, mode, 'aborted'))
-        mode_manager = objreg.get('mode-manager')
+        mode_manager = objreg.get('mode-manager', scope='window',
+                                  window=self._win_id)
         try:
             modeman.enter(self._win_id, mode, 'question asked')
         except modeman.ModeLockedError:
diff --git a/qutebrowser/widgets/tabbedbrowser.py b/qutebrowser/widgets/tabbedbrowser.py
index 634f6ee90..6e49d37ee 100644
--- a/qutebrowser/widgets/tabbedbrowser.py
+++ b/qutebrowser/widgets/tabbedbrowser.py
@@ -99,7 +99,7 @@ class TabbedBrowser(tabwidget.TabWidget):
     title_changed = pyqtSignal(str)
 
     def __init__(self, win_id, parent=None):
-        super().__init__(parent)
+        super().__init__(win_id, parent)
         self._win_id = win_id
         self._tab_insert_idx_left = 0
         self._tab_insert_idx_right = -1
diff --git a/qutebrowser/widgets/tabwidget.py b/qutebrowser/widgets/tabwidget.py
index 354519f7b..10b3b0f13 100644
--- a/qutebrowser/widgets/tabwidget.py
+++ b/qutebrowser/widgets/tabwidget.py
@@ -42,9 +42,9 @@ class TabWidget(QTabWidget):
 
     """The tabwidget used for TabbedBrowser."""
 
-    def __init__(self, parent=None):
+    def __init__(self, win_id, parent=None):
         super().__init__(parent)
-        bar = TabBar()
+        bar = TabBar(win_id)
         self.setTabBar(bar)
         bar.tabCloseRequested.connect(self.tabCloseRequested)
         self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
@@ -90,10 +90,12 @@ class TabBar(QTabBar):
 
     Attributes:
         vertical: When the tab bar is currently vertical.
+        win_id: The window ID this TabBar belongs to.
     """
 
-    def __init__(self, parent=None):
+    def __init__(self, win_id, parent=None):
         super().__init__(parent)
+        self._win_id = win_id
         self.setStyle(TabBarStyle(self.style()))
         self.set_font()
         config.on_change(self.set_font, 'fonts', 'tabbar')
@@ -200,8 +202,10 @@ class TabBar(QTabBar):
         if self.vertical:
             confwidth = str(config.get('tabs', 'width'))
             if confwidth.endswith('%'):
+                main_window = objreg.get('main-window', scope='window',
+                                         window=self._win_id)
                 perc = int(confwidth.rstrip('%'))
-                width = objreg.get('main-window').width() * perc / 100
+                width = main_window.width() * perc / 100
             else:
                 width = int(confwidth)
             size = QSize(max(minimum_size.width(), width), height)
diff --git a/qutebrowser/widgets/webview.py b/qutebrowser/widgets/webview.py
index 033a56cae..97a021b7d 100644
--- a/qutebrowser/widgets/webview.py
+++ b/qutebrowser/widgets/webview.py
@@ -366,7 +366,9 @@ class WebView(QWebView):
             self._set_load_status(LoadStatus.error)
         if not config.get('input', 'auto-insert-mode'):
             return
-        cur_mode = objreg.get('mode-manager').mode()
+        mode_manager = objreg.get('mode-manager', scope='window',
+                                  window=self._win_id)
+        cur_mode = mode_manager.mode()
         if cur_mode == usertypes.KeyMode.insert or not ok:
             return
         frame = self.page().currentFrame()
@@ -413,7 +415,9 @@ class WebView(QWebView):
         if wintype == QWebPage.WebModalDialog:
             log.webview.warning("WebModalDialog requested, but we don't "
                                 "support that!")
-        return objreg.get('tabbed-browser').tabopen()
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window=self._win_id)
+        return tabbed_browser.tabopen()
 
     def paintEvent(self, e):
         """Extend paintEvent to emit a signal if the scroll position changed.