Add an example for multiple Window.on_dropfile

examples/miscellaneous/multiple_dropfile.py

@@ -0,0 +1,50 @@
+from kivy.app import App
+from kivy.uix.button import Button
+from kivy.core.window import Window
+from kivy.uix.boxlayout import BoxLayout
+
+
+class DropFile(Button):
+    def __init__(self, **kwargs):
+        super(DropFile, self).__init__(**kwargs)
+
+        # get app instance to add function from widget
+        app = App.get_running_app()
+
+        # add function to the list
+        app.drops.append(self.on_dropfile)
+
+    def on_dropfile(self, widget, filename):
+        # a function catching a dropped file
+        # if it's dropped in the widget's area
+        if self.collide_point(*Window.mouse_pos):
+            # on_dropfile's filename is bytes (py3)
+            self.text = filename.decode('utf-8')
+
+
+class DropApp(App):
+    def build(self):
+        # set an empty list that will be later populated
+        # with functions from widgets themselves
+        self.drops = []
+
+        # bind handling function to 'on_dropfile'
+        Window.bind(on_dropfile=self.handledrops)
+
+        box = BoxLayout()
+        dropleft = DropFile(text='left')
+        box.add_widget(dropleft)
+        dropright = DropFile(text='right')
+        box.add_widget(dropright)
+        return box
+
+    def handledrops(self, *args):
+        # this will execute each function from list with arguments from
+        # Window.on_dropfile
+        #
+        # make sure `Window.on_dropfile` works on your system first,
+        # otherwise the example won't work at all
+        for func in self.drops:
+            func(*args)
+
+DropApp().run()