Merge from 5.x: PR #15172

Fixes #15164

.github/scripts/install.sh

@@ -30,6 +30,9 @@ if [ "$USE_CONDA" = "true" ]; then
     # Remove packages we have subrepos for
     conda remove spyder-kernels --force -q -y
     conda remove python-language-server --force -q -y
+
+    # Provisional change to prevent error from jupyter_client 6.1.13
+    conda install jupyter_client=6.1.12
 else
     # Update pip and setuptools
     pip install -U pip setuptools
@@ -52,6 +55,9 @@ else
     # Remove packages we have subrepos for
     pip uninstall spyder-kernels -q -y
     pip uninstall python-language-server -q -y
+
+    # Provisional change to prevent error from jupyter_client 6.1.13
+    pip install jupyter_client==6.1.12
 fi
 
 # This is necessary only for Windows (don't know why).

spyder/app/mainwindow.py

@@ -344,6 +344,21 @@ def last_plugin(self):
         # spyder/plugins/base::_switch_to_plugin
         return self.layouts.get_last_plugin()
 
+    def maximize_dockwidget(self, restore=False):
+        """
+        This is needed to prevent errors with the old API at
+        spyder/plugins/base::_switch_to_plugin.
+
+        See spyder-ide/spyder#15164
+
+        Parameters
+        ----------
+        restore : bool, optional
+            If the current dockwidget needs to be restored to its unmaximized
+            state. The default is False.
+        """
+        self.layouts.maximize_dockwidget(restore=restore)
+
     def switch_to_plugin(self, plugin, force_focus=None):
         """
         Switch to this plugin.