comments for back-button fix

Author: micahscopes

pythonforandroid/bootstraps/webview/build/src/main/java/org/kivy/android/PythonActivity.java

@@ -272,12 +272,16 @@ public static ViewGroup getLayout() {
     long lastBackClick = SystemClock.elapsedRealtime();
     @Override
     public boolean onKeyDown(int keyCode, KeyEvent event) {
-        // Check if the key event was the Back button and if there's history
+        // Check if the key event was the Back button
         if ((keyCode == KeyEvent.KEYCODE_BACK)) {
+            // If there's some web history, go back
             if(mWebView.canGoBack()) {
                 mWebView.goBack();
                 return true;
             }
+            // Otherwise, if it's been a little while since the Back key was
+            // last pressed, register that it's been pressed and notify the
+            // user that pressing it again will close the app.
             if (SystemClock.elapsedRealtime() - lastBackClick > 2000){
                 lastBackClick = SystemClock.elapsedRealtime();
                 Toast.makeText(this, "Click again to close the app",
@@ -286,8 +290,9 @@ public boolean onKeyDown(int keyCode, KeyEvent event) {
             }
         }
 
-        // If it wasn't the Back key or there's no web page history, bubble up to the default
-        // system behavior (probably exit the activity)
+        // If it wasn't the Back key, or if the user tapped the Back key twice, 
+        // quickly and without web history, bubble up to the default system
+        // behavior (probably exit the activity)
         return super.onKeyDown(keyCode, event);
     }