Add BackPressed event.

Change-Id: I18b30064a90d55759f52388c9a413242d1861b85

appinventor/appengine/src/com/google/appinventor/client/youngandroid/YoungAndroidFormUpgrader.java

@@ -610,6 +610,10 @@ public final class YoungAndroidFormUpgrader {
       // to be modified to upgrade to version 9.
       srcCompVersion = 9;
     }
+    if (srcCompVersion < 10) {
+      // The BackPressed event was added. No blocks need to be modified to upgrade to version 10.
+      srcCompVersion = 10;
+    }
     return srcCompVersion;
   }
 

appinventor/blockslib/src/openblocks/yacodeblocks/BlockSaveFile.java

@@ -789,6 +789,10 @@ public class BlockSaveFile {
       // to be modified to upgrade to version 9.
       blkCompVersion = 9;
     }
+    if (blkCompVersion < 10) {
+      // The BackPressed event was added. No blocks need to be modified to upgrade to version 10.
+      blkCompVersion = 10;
+    }
     return blkCompVersion;
   }
 

appinventor/components/src/com/google/appinventor/components/common/YaVersion.java

@@ -201,8 +201,10 @@ public class YaVersion {
   // - BALL_COMPONENT_VERSION was incremented to 5.
   // - CANVAS_COMPONENT_VERSION was incremented to 7.
   // - IMAGESPRITE_COMPONENT_VERSION was incremented to 6.
+  // For YOUNG_ANDROID_VERSION 66:
+  // - FORM_COMPONENT_VERSION was incremented to 10.
 
-    public static final int YOUNG_ANDROID_VERSION = 65;
+    public static final int YOUNG_ANDROID_VERSION = 66;
 
   // ............................... Blocks Language Version Number ...............................
 
@@ -387,7 +389,9 @@ public class YaVersion {
   // For FORM_COMPONENT_VERSION 9:
   // - The OpenScreenAnimation property was added
   // - The CloseScreenAnimation property was added
-  public static final int FORM_COMPONENT_VERSION = 9;
+  // For FORM_COMPONENT_VERSION 10:
+  // - The BackPressed event was added.
+  public static final int FORM_COMPONENT_VERSION = 10;
 
   // For FUSIONTABLESCONTROL_COMPONENT_VERSION 2:
   // - The Fusiontables API was migrated from SQL to V1

appinventor/components/src/com/google/appinventor/components/runtime/Form.java

@@ -243,13 +243,22 @@ public class Form extends Activity
   @Override
   public boolean onKeyDown(int keyCode, KeyEvent event) {
     if (keyCode == KeyEvent.KEYCODE_BACK) {      
+      if (!BackPressed()) {
         boolean handled = super.onKeyDown(keyCode, event);
         AnimationUtil.ApplyCloseScreenAnimation(this, closeAnimType);
         return handled;
+      } else {
+        return true;
+      }      
     }
     return super.onKeyDown(keyCode, event);
   }
 
+  @SimpleEvent(description = "Device back button pressed.")
+  public boolean BackPressed() {
+    return EventDispatcher.dispatchEvent(this, "BackPressed");
+  }
+  
   // onActivityResult should be triggered in only two cases:
   // (1) The result is for some other component in the app, not this Form itself
   // (2) This page started another page, and that page is closing, and passing