diff --git a/coretk/coretk/app.py b/coretk/coretk/app.py
new file mode 100644
index 00000000..cc664923
--- /dev/null
+++ b/coretk/coretk/app.py
@@ -0,0 +1,68 @@
+import tkinter as tk
+
+from coretk.graph import CanvasGraph
+
+
+class Application(tk.Frame):
+    def __init__(self, master=None):
+        super().__init__(master)
+        self.pack(fill=tk.BOTH, expand=1)
+        self.images = []
+        self.menubar = None
+        self.create_menu()
+        self.create_widgets()
+
+    def create_menu(self):
+        self.master.option_add("*tearOff", tk.FALSE)
+        self.menubar = tk.Menu(self.master)
+        file_menu = tk.Menu(self.menubar)
+        file_menu.add_command(label="Open")
+        file_menu.add_command(label="Exit", command=root.quit)
+        self.menubar.add_cascade(label="File", menu=file_menu)
+        help_menu = tk.Menu(self.menubar)
+        self.menubar.add_cascade(label="Help", menu=help_menu)
+        self.master.config(menu=self.menubar)
+
+    def create_widgets(self):
+        edit_frame = tk.Frame(self)
+        edit_frame.pack(side=tk.LEFT, fill=tk.Y, ipadx=2, ipady=2)
+        b = tk.Button(edit_frame, text="Button 1")
+        b.pack(side=tk.TOP, pady=1)
+        b = tk.Button(edit_frame, text="Button 2")
+        b.pack(side=tk.TOP, pady=1)
+        b = tk.Button(edit_frame, text="Button 3")
+        b.pack(side=tk.TOP, pady=1)
+
+        self.canvas = CanvasGraph(
+            self, background="#cccccc", scrollregion=(0, 0, 1000, 1000)
+        )
+        self.canvas.load("switch", "switch.png")
+        self.canvas.add_node(50, 50, "Node 1", "switch")
+        self.canvas.add_node(50, 100, "Node 2", "switch")
+        self.canvas.pack(fill=tk.BOTH, expand=True)
+        scroll_x = tk.Scrollbar(
+            self.canvas, orient=tk.HORIZONTAL, command=self.canvas.xview
+        )
+        scroll_x.pack(side=tk.BOTTOM, fill=tk.X)
+        scroll_y = tk.Scrollbar(self.canvas, command=self.canvas.yview)
+        scroll_y.pack(side=tk.RIGHT, fill=tk.Y)
+        self.canvas.configure(xscrollcommand=scroll_x.set)
+        self.canvas.configure(yscrollcommand=scroll_y.set)
+
+        status_bar = tk.Frame(self)
+        status_bar.pack(side=tk.BOTTOM, fill=tk.X)
+        b = tk.Button(status_bar, text="Button 1")
+        b.pack(side=tk.LEFT, padx=1)
+        b = tk.Button(status_bar, text="Button 2")
+        b.pack(side=tk.LEFT, padx=1)
+        b = tk.Button(status_bar, text="Button 3")
+        b.pack(side=tk.LEFT, padx=1)
+
+
+if __name__ == "__main__":
+    root = tk.Tk()
+    root.title("Graph Canvas")
+    root.geometry("800x600")
+    root.state("zoomed")
+    app = Application(master=root)
+    app.mainloop()
diff --git a/coretk/coretk/graph.py b/coretk/coretk/graph.py
index 8de6ef81..d6e73e3c 100644
--- a/coretk/coretk/graph.py
+++ b/coretk/coretk/graph.py
@@ -219,68 +219,3 @@ class CanvasNode:
 
     def context(self, event):
         print(f"context click {self.name}: {event}")
-
-
-class Application(tk.Frame):
-    def __init__(self, master=None):
-        super().__init__(master)
-        self.pack(fill=tk.BOTH, expand=1)
-        self.images = []
-        self.menubar = None
-        self.create_menu()
-        self.create_widgets()
-
-    def create_menu(self):
-        self.master.option_add("*tearOff", tk.FALSE)
-        self.menubar = tk.Menu(self.master)
-        file_menu = tk.Menu(self.menubar)
-        file_menu.add_command(label="Open")
-        file_menu.add_command(label="Exit", command=root.quit)
-        self.menubar.add_cascade(label="File", menu=file_menu)
-        help_menu = tk.Menu(self.menubar)
-        self.menubar.add_cascade(label="Help", menu=help_menu)
-        self.master.config(menu=self.menubar)
-
-    def create_widgets(self):
-        edit_frame = tk.Frame(self)
-        edit_frame.pack(side=tk.LEFT, fill=tk.Y, ipadx=2, ipady=2)
-        b = tk.Button(edit_frame, text="Button 1")
-        b.pack(side=tk.TOP, pady=1)
-        b = tk.Button(edit_frame, text="Button 2")
-        b.pack(side=tk.TOP, pady=1)
-        b = tk.Button(edit_frame, text="Button 3")
-        b.pack(side=tk.TOP, pady=1)
-
-        self.canvas = CanvasGraph(
-            self, background="#cccccc", scrollregion=(0, 0, 1000, 1000)
-        )
-        self.canvas.load("switch", "switch.png")
-        self.canvas.add_node(50, 50, "Node 1", "switch")
-        self.canvas.add_node(50, 100, "Node 2", "switch")
-        self.canvas.pack(fill=tk.BOTH, expand=True)
-        scroll_x = tk.Scrollbar(
-            self.canvas, orient=tk.HORIZONTAL, command=self.canvas.xview
-        )
-        scroll_x.pack(side=tk.BOTTOM, fill=tk.X)
-        scroll_y = tk.Scrollbar(self.canvas, command=self.canvas.yview)
-        scroll_y.pack(side=tk.RIGHT, fill=tk.Y)
-        self.canvas.configure(xscrollcommand=scroll_x.set)
-        self.canvas.configure(yscrollcommand=scroll_y.set)
-
-        status_bar = tk.Frame(self)
-        status_bar.pack(side=tk.BOTTOM, fill=tk.X)
-        b = tk.Button(status_bar, text="Button 1")
-        b.pack(side=tk.LEFT, padx=1)
-        b = tk.Button(status_bar, text="Button 2")
-        b.pack(side=tk.LEFT, padx=1)
-        b = tk.Button(status_bar, text="Button 3")
-        b.pack(side=tk.LEFT, padx=1)
-
-
-if __name__ == "__main__":
-    root = tk.Tk()
-    root.title("Graph Canvas")
-    root.geometry("800x600")
-    root.state("zoomed")
-    app = Application(master=root)
-    app.mainloop()