adding redo functionality

src/GUI.py

@@ -91,6 +91,7 @@ class GUI:
         edit_menu = tk.Menu(menu, tearoff=0)
         menu.add_cascade(label="Edit", menu=edit_menu)
         edit_menu.add_command(label="Undo", accelerator="Ctrl+Z", command=lambda: self._undo())
+        edit_menu.add_command(label="Redo", accelerator="Ctrl+Y", command=lambda: self._redo())
         edit_menu.add_separator()
         edit_menu.add_command(label="Toggle Selection Mode", accelerator="Ctrl+S", command=lambda: self._toggleSelectionMode())
 
@@ -118,6 +119,7 @@ class GUI:
 
         # Key bindings
         root.bind_all('<Control-z>', lambda event: self._undo())
+        root.bind_all('<Control-y>', lambda event: self._redo())
         root.bind_all('<Control-s>', lambda event: self._toggleSelectionMode())
 
         root.mainloop()
@@ -184,6 +186,12 @@ class GUI:
         self._currentImage.undo()
         self._renderCurrentImage()
 
+    def _redo(self) -> None:
+        if self._currentImage is None:
+            return
+        self._currentImage.redo()
+        self._renderCurrentImage()
+
     def _toggleSelectionMode(self) -> None:
         """Toggle interactive selection mode on/off."""
         self._selectionMode = not self._selectionMode