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Android widgets in keyguard, handle onClick events

I hope this question wasn´t asked before, but I couldn´t find any solution for my problem. I have a widget which is also used for keyguard. I want to add an onClick handler for my widget. There is no problem, when the widget is on home-screen, the activity starts normally. But on keyguard the activity is launched, but isn´t shown, because the device is locked.
I don´t want to dismiss the keyguard with flags like WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED and WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD. I just want a little window to be shown, where I am asked to unlock the device, like it is opened when you click on several keyguard widgets, like for the android e-mail application.
Is there another flag to achieve this? Or do I have to do something with my intent, called to open the activity? Thanks for help.

For enabling or disabling lock screen in Android, we need to get the instance of keyBoard Manager, using getSystemService(). The syntax is as,
KeyguardManager keyguardManager =
(KeyguardManager)getSystemService(Activity.KEYGUARD_SERVICE);
KeyguardLock lock = keyguardManager.newKeyguardLock(KEYGUARD_SERVICE);
For locking the screen use,
lock.reenableKeyguard();
and for disabling the lock use,
lock.disableKeyguard();
This will just hide the lock screen and will display if any incoming call or any such event is happening, it will display that screen. It wont display the lock screen.
When running the application, to disable from going to the lock state, just use
setKeepScreenOn() is set to true. or use the xml attribute android:keepScreenOn="true"
Another way to prevent the device to go to the sleep or lock mode when the application is running is set this api to true - setKeepScreenOn()
And of course we need to give permission android.permission.DISABLE_KEYGUARD

keep android screen from dimming while activity is running

For my android app, I want to keep the screen from dimming while certain activities (e.g. CatActivity) are in the resume state. Does anyone know how to do that? is there a way to declare so in the manifest or in the activity itself?
UPDATE
I found the answer:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
Is there a way to turn it off? I don't see a removeFlags method.

To delete the flag simply call the clearFlags() method:
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

Android: How To Start An Activity When Screen Locked

I'm developing a VOIP liked app and I want to receive a call when my phone is screen locked.
Also, if I set the lock pattern for my phone, I want to show the activity before I make the unlock pattern. Could you please help to give me any advice or example?
Thanks very much.

Try this it will open screen lock
Window wind;
wind = this.getWindow();
wind.addFlags(LayoutParams.FLAG_DISMISS_KEYGUARD);
wind.addFlags(LayoutParams.FLAG_SHOW_WHEN_LOCKED);

Thanks, I 'm following your indication and it do resolve my problem, also as below:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
But the call sequence of Activity callback is very strange, it will call onStart(), onResume(), onPause(), onStop(), then recall onStart(), onPause() suddenly. And because I finish() the Activity when onPause(), so I incorrectly believe the Activity is nevery resumed. Thanks again for your help.

override power button callback

Is it possible in an acitvity override the callback called when the power button is pressed? My target is to prevent the screen off.
I found this - How to hook into the Power button in Android? -but it seems don't work.
THX

You can keep the screen on with a wake lock:
http://developer.android.com/reference/android/os/PowerManager.html
But you should be carefull with it because it really drains the battery.

Enable or disable the PatternLock screen from code

I have tried to find a way to disable the PatternLock screen temporarily. I don't want the lock to be disabled completely, but the user should not need to re-enter his pattern all the time.
My idea is to write a service which disables the pattern after some user activity and re-enables it after a while. (and even more)
There are apps on the market that do something like that (i.e. AutoLock or TogglePattern), so there must be a solution.
I know that I can prevent a lock completely by using:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
or
KeyguardLock.disableKeyguard()
But that is not what I'm after.
I saw the class com.android.internal.widget.LockPatternUtils in the android sources which is used by the settings activity, but this class is not (at least as far as I know) accessible by a "normal" application.
Do you have any suggestions?

As of 2.0 (API level 5), you can use this window flag to prevent the lock screen from being displayed while your window is shown:
http://developer.android.com/reference/android/view/WindowManager.LayoutParams.html#FLAG_SHOW_WHEN_LOCKED
You can also use this flag to allow a non-secure keyguard to be dismissed when your window is displayed:
http://developer.android.com/reference/android/view/WindowManager.LayoutParams.html#FLAG_DISMISS_KEYGUARD
Note that these do not allow you to bypass the lock screen outside of your application's environment, which is an intentional design decision.
There is also an older API that lets you hide the lock screen in a similar way to a wake lock:
http://developer.android.com/reference/android/app/KeyguardManager.html#newKeyguardLock(java.lang.String)
Use of this API is discouraged on newer platforms, because it is very easy to get wrong and cause bad behavior (the screen not locking when the user would expect it to), and basically impossible to have clean transitions between activities with unlocked states. For example, this is the API that the in-call screen originally used to hide the lock screen when it was displayed, but as of 2.0 it has switched to the new cleaner window flags. Likewise for the alarm clock etc.

Have you tried looking at the code for com.android.internal.widget.LockPatternUtils and doing what it does?
It has something like this:
public void setLockPatternEnabled(boolean enabled) {
setBoolean(android.provider.Settings.System.LOCK_PATTERN_ENABLED, enabled);
}
private void setBoolean(String systemSettingKey, boolean enabled) {
android.provider.Settings.System.putInt(
mContentResolver,
systemSettingKey,
enabled ? 1 : 0);
}
You might be able to do something similar in your code.