Update for Issue pythonarcade#26, having example code with window res…

…izing.

doc/examples/resizable_window.rst

@@ -1,4 +1,6 @@
-.. _resizable-window:
+:orphan:
+
+.. _resizable_window:
 
 Resizable Window
 ================

examples/resizable_window.py

@@ -0,0 +1,62 @@
+"""
+Example showing how handle screen resizing.
+"""
+import arcade
+
+SCREEN_WIDTH = 500
+SCREEN_HEIGHT = 500
+START = 0
+END = 2000
+STEP = 50
+
+
+class MyApplication(arcade.Window):
+    """
+    Main application class.
+    """
+
+    def __init__(self, width, height):
+        super().__init__(width, height, title="Resizing Window Example", resizable=True)
+
+        arcade.set_background_color(arcade.color.WHITE)
+
+        # Create some text labels for our coordinates
+        self.label_list = []
+        for y in range(START, END, STEP):
+            my_text = arcade.create_text(f"{y}", arcade.color.BLACK, 12, anchor_x="left", anchor_y="bottom")
+            self.label_list.append(my_text)
+
+    def on_resize(self, width, height):
+        """ This method is automatically called when the window is resized. """
+
+        # Call the parent. Failing to do this will mess up the coordinates, and default to 0,0 at the center and the
+        # edges being -1 to 1.
+        super().on_resize(width, height)
+
+        print(f"Window resized to: {width}, {height}")
+
+    def on_draw(self):
+        """ Render the screen. """
+
+        arcade.start_render()
+
+        # Draw the y labels
+        i = 0
+        for y in range(START, END, STEP):
+            arcade.draw_point(0, y, arcade.color.BLUE, 5)
+            arcade.render_text(self.label_list[i], 5, y)
+            i += 1
+
+        # Draw the x labels.
+        i = 1
+        for x in range(START + STEP, END, STEP):
+            arcade.draw_point(x, 0, arcade.color.BLUE, 5)
+            arcade.render_text(self.label_list[i], x, 5)
+            i += 1
+
+
+def main():
+    MyApplication(SCREEN_WIDTH, SCREEN_HEIGHT)
+    arcade.run()
+
+main()