Demonstration of how to get the value as we don't want actual saving done in this script

prompt_window.py

@@ -15,7 +15,10 @@ class PromptWindow(Gtk.Window):
         self.set_size_request(500, 100)
         self.set_border_width(10)
 
-        vbox = Gtk.Box(spacing=10)
+        # This is needed to end the thread if the dialog is closed with the X.
+        self.connect("destroy", Gtk.main_quit)
+
+        vbox = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
         self.add(vbox)
 
         self.entry = Gtk.Entry()
@@ -38,12 +41,16 @@ class PromptWindow(Gtk.Window):
     def save(self, item):
         # Note: item is the entry directly if enter is pressed, but the button
         # (i guess) if the button is pressed, so we do not use it.
-        task = self.entry.get_text()
-        print(task)
+        self.task = self.entry.get_text()
         # A little concerned this might be sort of the nuclear option here.
         Gtk.main_quit()
 
+    def retrieve(self):
+        return self.task
+
 
 win = PromptWindow(task="Making money")
 win.show_all()
 Gtk.main()
+tha_task = win.retrieve()
+print(tha_task)