diff --git a/common/tksimpledialog.py b/common/tksimpledialog.py
new file mode 100755
index 0000000..4734291
--- /dev/null
+++ b/common/tksimpledialog.py
@@ -0,0 +1,86 @@
+#!/usr/bin/env python3
+#
+# Dialog class for tkinter
+
+import os
+import tkinter
+from tkinter import ttk
+
+class Dialog(tkinter.Toplevel):
+
+    def __init__(self, parent, message = None, title = None, seed = None, border = 'blue', **kwargs):
+
+        tkinter.Toplevel.__init__(self, parent)
+        self.transient(parent)
+
+        if title:
+            self.title(title)
+
+        self.configure(background=border, padx=2, pady=2)
+        self.obox = ttk.Frame(self)
+        self.obox.pack(side = 'left', fill = 'both', expand = 'true')
+
+        self.parent = parent
+        self.result = None
+        body = ttk.Frame(self.obox)
+        self.initial_focus = self.body(body, message, seed, **kwargs)
+        body.pack(padx = 5, pady = 5)
+        self.buttonbox()
+        self.grab_set()
+
+        if not self.initial_focus:
+            self.initial_focus = self
+
+        self.protocol("WM_DELETE_WINDOW", self.cancel)
+        self.geometry("+%d+%d" % (parent.winfo_rootx() + 50,
+                                  parent.winfo_rooty() + 50))
+
+        self.initial_focus.focus_set()
+        self.wait_window(self)
+
+    # Construction hooks
+
+    def body(self, master, **kwargs):
+        # Create dialog body.  Return widget that should have
+        # initial focus.  This method should be overridden
+        pass
+
+    def buttonbox(self):
+        # Add standard button box.  Override if you don't want the
+        # standard buttons
+
+        box = ttk.Frame(self.obox)
+
+        self.okb = ttk.Button(box, text="OK", width=10, command=self.ok, default='active')
+        self.okb.pack(side='left', padx=5, pady=5)
+        w = ttk.Button(box, text="Cancel", width=10, command=self.cancel)
+        w.pack(side='left', padx=5, pady=5)
+
+        self.bind("<Return>", self.ok)
+        self.bind("<Escape>", self.cancel)
+        box.pack(fill='x', expand='true')
+
+    # Standard button semantics
+
+    def ok(self, event=None):
+
+        if not self.validate():
+            self.initial_focus.focus_set() # put focus back
+            return
+
+        self.withdraw()
+        self.update_idletasks()
+        self.result = self.apply()
+        self.cancel()
+
+    def cancel(self, event=None):
+
+        # Put focus back to the parent window
+        self.parent.focus_set()
+        self.destroy()
+
+    def validate(self):
+        return 1 # Override this
+
+    def apply(self):
+        return None # Override this