Allow undoing color or character information loss

Of course, this highlights the need to prompt during Save as well,
not just Save As, or to make creating color or character information
impossible depending on the type of file that is open.

cspell.json

@@ -45,6 +45,7 @@
 		"getpixel",
 		"goland",
 		"gvim",
+		"hackily",
 		"Haha",
 		"hkey",
 		"hslrgb",

src/textual_paint/paint.py

@@ -2606,7 +2606,7 @@ class PaintApp(App[None]):
                         self.saved_undo_count = len(self.undos)
                         window.close()
                         if reload_after_save:
-                            # TODO: make this undoable
+                            self.resize_document(self.image.width, self.image.height) # (hackily) make this undoable
                             new_image = AnsiArtDocument.decode_based_on_file_extension(content, file_path)
                             self.canvas.image = self.image = new_image
                             self.canvas.refresh(layout=True)
@@ -3269,7 +3269,7 @@ class PaintApp(App[None]):
         self.cancel_preview()
 
         # NOTE: This function is relied on to create an undo even if the size doesn't change,
-        # when recovering from a backup.
+        # when recovering from a backup, and when reloading file content when losing information during Save As.
         # TODO: DRY undo state creation (at least the undos/redos part)
         action = Action(_("Attributes"), Region(0, 0, self.image.width, self.image.height))
         action.is_resize = True