Add quit button with unsaved changes warning in PhotoTagger

This update introduces a new quit button that prompts users with a warning if there are unsaved changes before exiting the tagging dialog. The warning summarizes pending tag additions and removals, allowing users to choose to save changes, quit without saving, or cancel the action. Additionally, the tag selection combobox is now set to 'readonly' to prevent user modifications, enhancing the overall user experience in managing photo tags.

photo_tagger.py

@@ -4613,6 +4613,46 @@ class PhotoTagger:
         save_button = ttk.Button(bottom_frame, text="Save Tagging")
         save_button.pack(side=tk.RIGHT, padx=10, pady=5)
         
+        # Quit button with warning for pending changes
+        def quit_with_warning():
+            """Quit the dialog, but warn if there are pending changes"""
+            # Check for pending changes
+            has_pending_changes = bool(pending_tag_changes or pending_tag_removals)
+            
+            if has_pending_changes:
+                total_additions = sum(len(tags) for tags in pending_tag_changes.values())
+                total_removals = sum(len(tags) for tags in pending_tag_removals.values())
+                
+                changes_text = []
+                if total_additions > 0:
+                    changes_text.append(f"{total_additions} tag addition(s)")
+                if total_removals > 0:
+                    changes_text.append(f"{total_removals} tag removal(s)")
+                
+                changes_summary = " and ".join(changes_text)
+                
+                result = messagebox.askyesnocancel(
+                    "Unsaved Changes", 
+                    f"You have unsaved changes: {changes_summary}.\n\n"
+                    "Do you want to save your changes before quitting?\n\n"
+                    "Yes = Save and quit\n"
+                    "No = Quit without saving\n"
+                    "Cancel = Stay in dialog"
+                )
+                
+                if result is True:  # Yes - Save and quit
+                    save_tagging_changes()
+                    root.destroy()
+                elif result is False:  # No - Quit without saving
+                    root.destroy()
+                # If result is None (Cancel), do nothing - stay in dialog
+            else:
+                # No pending changes, just quit
+                root.destroy()
+        
+        quit_button = ttk.Button(bottom_frame, text="Quit", command=quit_with_warning)
+        quit_button.pack(side=tk.RIGHT, padx=(0, 10), pady=5)
+        
         # Enable mouse scroll anywhere in the dialog
         def on_mousewheel(event):
             content_canvas.yview_scroll(int(-1*(event.delta/120)), "units")
@@ -5153,7 +5193,7 @@ class PhotoTagger:
                 # Top frame - dropdown to select tag to add
                 ttk.Label(top_frame, text="Add tag:").grid(row=0, column=0, padx=(0, 8), sticky=tk.W)
                 tag_var = tk.StringVar()
-                combo = ttk.Combobox(top_frame, textvariable=tag_var, values=available_tags, width=30)
+                combo = ttk.Combobox(top_frame, textvariable=tag_var, values=available_tags, width=30, state='readonly')
                 combo.grid(row=0, column=1, padx=(0, 8), sticky=(tk.W, tk.E))
                 combo.focus_set()