When pass code is enabled, the app is sent to background if the screen is turned off and the windows are made secure to prevent they are rendered in the 'recents' menu

src/com/owncloud/android/MainApp.java

@@ -88,6 +88,7 @@ public class MainApp extends Application {
                 @Override
                 public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
                     Log_OC.d(activity.getClass().getSimpleName(),  "onCreate(Bundle) starting" );
+                    PassCodeManager.getPassCodeManager().onActivityCreated(activity);
                 }
 
                 @Override

src/com/owncloud/android/authentication/PassCodeManager.java

@@ -1,9 +1,13 @@
 package com.owncloud.android.authentication;
 
 import android.app.Activity;
+import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
+import android.os.PowerManager;
 import android.preference.PreferenceManager;
+import android.view.View;
+import android.view.WindowManager;
 
 import com.owncloud.android.MainApp;
 import com.owncloud.android.ui.activity.PinCodeActivity;
@@ -22,7 +26,7 @@ public class PassCodeManager {
     }
 
     private static int PASS_CODE_TIMEOUT = 1000;
-        // keeping a "low" value (not 0) is the easiest way to avoid prevent the pass code is requested on rotations
+        // keeping a "low" positive value is the easiest way to prevent the pass code is requested on rotations
 
     public static PassCodeManager mPassCodeManagerInstance = null;
 
@@ -38,6 +42,14 @@ public class PassCodeManager {
 
     protected PassCodeManager() {};
 
+    public void onActivityCreated(Activity activity) {
+        if (passCodeIsEnabled()) {
+            activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
+        } else {
+            activity.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_SECURE);
+        }
+    }
+
     public void onActivityStarted(Activity activity) {
         if (!sExemptOfPasscodeActivites.contains(activity.getClass()) &&
                 passCodeShouldBeRequested()
@@ -47,9 +59,10 @@ public class PassCodeManager {
             i.setAction(PinCodeActivity.ACTION_REQUEST);
             i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
             activity.startActivity(i);
+
         }
 
-        mVisibleActivitiesCounter++;    // AFTER passCodeShouldBeRequested was checked
+        mVisibleActivitiesCounter++;    // keep it AFTER passCodeShouldBeRequested was checked
     }
 
     public void onActivityStopped(Activity activity) {
@@ -57,22 +70,28 @@ public class PassCodeManager {
             mVisibleActivitiesCounter--;
         }
         setUnlockTimestamp();
+        PowerManager powerMgr = (PowerManager) activity.getSystemService(Context.POWER_SERVICE);
+        if (passCodeIsEnabled() && powerMgr != null && !powerMgr.isScreenOn()) {
+            activity.moveTaskToBack(true);
+        }
+    }
+
+    private void setUnlockTimestamp() {
+        mTimestamp = System.currentTimeMillis();
     }
 
     private boolean passCodeShouldBeRequested(){
         if ((System.currentTimeMillis() - mTimestamp) > PASS_CODE_TIMEOUT &&
                 mVisibleActivitiesCounter <= 0
                 ){
-            SharedPreferences appPrefs = PreferenceManager.getDefaultSharedPreferences(MainApp.getAppContext());
-            if (appPrefs.getBoolean("set_pincode", false)) {
-                return true;
-            }
+            return passCodeIsEnabled();
         }
         return false;
     }
 
-    private void setUnlockTimestamp() {
-        mTimestamp = System.currentTimeMillis();
+    private boolean passCodeIsEnabled() {
+        SharedPreferences appPrefs = PreferenceManager.getDefaultSharedPreferences(MainApp.getAppContext());
+        return (appPrefs.getBoolean("set_pincode", false));
     }
 
 }

src/com/owncloud/android/ui/activity/FileDisplayActivity.java

@@ -65,7 +65,6 @@ import com.actionbarsherlock.view.Window;
 import com.owncloud.android.BuildConfig;
 import com.owncloud.android.MainApp;
 import com.owncloud.android.R;
-import com.owncloud.android.authentication.PassCodeManager;
 import com.owncloud.android.datamodel.OCFile;
 import com.owncloud.android.files.services.FileDownloader;
 import com.owncloud.android.files.services.FileDownloader.FileDownloaderBinder;