keep window size in single window mode even when no tab is opened. Fixes #7823

src/gui_interface.py

@@ -64,6 +64,7 @@ from chat_control import ChatControlBase
 from chat_control import ChatControl
 from groupchat_control import GroupchatControl
 from groupchat_control import PrivateChatControl
+from message_window import MessageWindowMgr
 
 from atom_window import AtomWindow
 from session import ChatControlSession
@@ -2710,6 +2711,10 @@ class Interface:
             self.show_systray()
 
         self.roster = roster_window.RosterWindow()
+        if self.msg_win_mgr.mode == \
+        MessageWindowMgr.ONE_MSG_WINDOW_ALWAYS_WITH_ROSTER:
+            self.msg_win_mgr.create_window(None, None, None)
+
         # Creating plugin manager
         import plugins
         gajim.plugin_manager = plugins.PluginManager()

src/message_window.py

@@ -601,7 +601,10 @@ class MessageWindow(object):
             ctrl.allow_shutdown(method, on_yes, on_no, on_minimize)
 
     def check_tabs(self):
-        if self.get_num_controls() == 0:
+        if self.parent_paned:
+            # Do nothing in single window mode
+            pass
+        elif self.get_num_controls() == 0:
             # These are not called when the window is destroyed like this, fake it
             gajim.interface.msg_win_mgr._on_window_delete(self.window, None)
             gajim.interface.msg_win_mgr._on_window_destroy(self.window)