Use a signal to request unmaximizing plugins

That way it'll be easier for external plugin developers to ask for this
programmatically.

spyder/api/plugins/new_api.py

@@ -269,6 +269,17 @@ class SpyderPluginV2(QObject, SpyderActionMixin, SpyderConfigurationObserver,
     To be used by plugins tracking main window position changes.
     """
 
+    sig_unmaximize_plugin_requested = Signal((), (object,))
+    """
+    This signal is emitted to inform the main window that it needs to
+    unmaximize the currently maximized plugin, if any.
+
+    Parameters
+    ----------
+    plugin_instance: SpyderDockablePlugin
+        Unmaximize plugin only if it is not `plugin_instance`.
+    """
+
     # --- Private attributes -------------------------------------------------
     # ------------------------------------------------------------------------
     # Define configuration name map for plugin to split configuration

spyder/app/mainwindow.py

@@ -225,6 +225,10 @@ def register_plugin(self, plugin_name, external=False, omit_conf=False):
             plugin.sig_focus_changed.connect(self.plugin_focus_changed)
             plugin.sig_switch_to_plugin_requested.connect(
                 self.switch_to_plugin)
+            plugin.sig_unmaximize_plugin_requested.connect(
+                self.unmaximize_plugin)
+            plugin.sig_unmaximize_plugin_requested[object].connect(
+                self.unmaximize_plugin)
             plugin.sig_update_ancestor_requested.connect(
                 lambda: plugin.set_ancestor(self))
 
@@ -357,6 +361,21 @@ def switch_to_plugin(self, plugin, force_focus=None):
         """
         self.layouts.switch_to_plugin(plugin, force_focus=force_focus)
 
+    def unmaximize_plugin(self, not_this_plugin=None):
+        """
+        Unmaximize currently maximized plugin, if any.
+
+        Parameters
+        ----------
+        not_this_plugin: SpyderDockablePlugin, optional
+            Unmaximize plugin if the maximized one is `not_this_plugin`.
+        """
+        if not_this_plugin is None:
+            self.layouts.unmaximize_dockwidget()
+        else:
+            self.layouts.unmaximize_other_dockwidget(
+                plugin_instance=not_this_plugin)
+
     def remove_dockwidget(self, plugin):
         """
         Remove a plugin QDockWidget from the main window.

spyder/plugins/ipythonconsole/plugin.py

@@ -40,7 +40,7 @@ class IPythonConsole(SpyderDockablePlugin):
 
     # This is required for the new API
     NAME = 'ipython_console'
-    REQUIRES = [Plugins.Console, Plugins.Preferences, Plugins.Layout]
+    REQUIRES = [Plugins.Console, Plugins.Preferences]
     OPTIONAL = [Plugins.Editor, Plugins.History, Plugins.MainMenu,
                 Plugins.Projects, Plugins.WorkingDirectory]
     TABIFY = [Plugins.History]
@@ -437,19 +437,6 @@ def _set_working_directory(self, new_dir):
         """Set current working directory on the main widget."""
         self.get_widget().set_working_directory(new_dir)
 
-    def _unmaximize_plugin(self):
-        """
-        Unmaximize the currently maximized plugin, if any.
-
-        Notes
-        -----
-        We assume that users want to check output in the IPython console
-        after running or debugging code. And for that we need to unmaximize any
-        plugin that is currently maximized.
-        """
-        layouts = self.get_plugin(Plugins.Layout)
-        layouts.unmaximize_dockwidget()
-
     # ---- Public API
     # -------------------------------------------------------------------------
 
@@ -663,7 +650,7 @@ def run_script(self, filename, wdir, args='', debug=False,
         -------
         None.
         """
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().run_script(
             filename,
             wdir,
@@ -704,7 +691,7 @@ def run_cell(self, code, cell_name, filename, run_cell_copy,
         -------
         None.
         """
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().run_cell(
             code, cell_name, filename, run_cell_copy, focus_to_editor,
             function=function)
@@ -734,7 +721,7 @@ def debug_cell(self, code, cell_name, filename, run_cell_copy,
         -------
         None.
         """
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().debug_cell(code, cell_name, filename, run_cell_copy,
                                      focus_to_editor)
 
@@ -764,12 +751,12 @@ def execute_code(self, lines, current_client=True, clear_variables=False):
 
     def run_selection(self, lines, focus_to_editor=True):
         """Execute selected lines in the current console."""
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().execute_code(lines, set_focus=not focus_to_editor)
 
     def stop_debugging(self):
         """Stop debugging in the current console."""
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().stop_debugging()
 
     def get_pdb_state(self):
@@ -795,7 +782,7 @@ def pdb_execute_command(self, command, focus_to_editor):
         -------
         None.
         """
-        self._unmaximize_plugin()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_widget().pdb_execute_command(command, focus_to_editor)
 
     def print_debug_file_msg(self):

spyder/plugins/projects/plugin.py

@@ -76,7 +76,7 @@ class Projects(SpyderDockablePlugin):
     NAME = 'project_explorer'
     CONF_SECTION = NAME
     CONF_FILE = False
-    REQUIRES = [Plugins.Layout]
+    REQUIRES = []
     OPTIONAL = [Plugins.Completions, Plugins.IPythonConsole, Plugins.Editor,
                 Plugins.MainMenu]
     WIDGET_CLASS = ProjectExplorerWidget
@@ -392,8 +392,7 @@ def on_close(self, cancelable=False):
     def unmaximize(self):
         """Unmaximize the currently maximized plugin, if not self."""
         if self.main:
-            layouts = self.get_plugin(Plugins.Layout)
-            layouts.unmaximize_other_dockwidget(plugin_instance=self)
+            self.sig_unmaximize_plugin_requested[object].emit(self)
 
     def build_opener(self, project):
         """Build function opening passed project"""

spyder/plugins/tours/plugin.py

@@ -33,7 +33,6 @@ class Tours(SpyderPluginV2):
     """
     NAME = 'tours'
     CONF_SECTION = NAME
-    REQUIRES = [Plugins.Layout]
     OPTIONAL = [Plugins.MainMenu]
     CONF_FILE = False
     CONTAINER_CLASS = ToursContainer
@@ -103,8 +102,7 @@ def show_tour(self, index):
         index: int
             The tour index to display.
         """
-        layouts = self.get_plugin(Plugins.Layout)
-        layouts.unmaximize_dockwidget()
+        self.sig_unmaximize_plugin_requested.emit()
         self.get_container().show_tour(index)
 
     def show_tour_message(self, force=False):