Open Last Item: Show an error message if no last item

Also de-duplicate the code

src/sgui/daw/item_editor/notes/__init__.py

@@ -398,7 +398,7 @@ def __init__(self):
             'Open the previously opened item.  Use this to rapidly switch '
             'between 2 items you are editing'
         )
-        self.open_last_action.triggered.connect(self.open_last)
+        self.open_last_action.triggered.connect(shared.open_last)
         self.open_last_action.setShortcut(
             QKeySequence.fromString("ALT+F"),
         )
@@ -465,14 +465,6 @@ def select_all(self):
         for f_note in shared.PIANO_ROLL_EDITOR.note_items:
             f_note.setSelected(True)
 
-    def open_last(self):
-        if shared.LAST_ITEM_NAME:
-            global_open_items(
-                shared.LAST_ITEM_NAME,
-                a_new_ref=shared.LAST_ITEM_REF,
-            )
-            shared.PIANO_ROLL_EDITOR.draw_item()
-
     def draw_last(self):
         shared.DRAW_LAST_ITEMS = not shared.DRAW_LAST_ITEMS
         self.draw_last_action.setChecked(shared.DRAW_LAST_ITEMS)

src/sgui/daw/shared.py

@@ -253,6 +253,15 @@ def open_last():
     if LAST_ITEM_NAME:
         global_open_items(LAST_ITEM_NAME, a_new_ref=LAST_ITEM_REF)
         MAIN_WINDOW.tab_changed()
+    else:
+        QMessageBox.warning(
+            None,
+            "Error",
+            (
+                "You musst open at least 2 items from the sequencer to use "
+                "this feature"
+            ),
+        )
 
 def global_open_project(a_project_file):
     """ Opens or creates a new project """