Dshow Camera capture application Problem in Windows Mobile

Dshow Camera capture application Problem in Windows Mobile:
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pimg.exe (Pictures and videos) behavior:
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if we are writing camera capture application, whenever the user hits Home button, the application must release the
Video and audio Capture Source; whenever the back button is pressed (if available) or Thru Task manager they switch to the Camera application ,
the camera capture application must starts its execution normally (render video from video source);
It makes use of the video and audio capture filters;
So Every camera capture application must follow this behavior;
I am writing the camera capture application, whenever the user hits the Home Button, the application focus is changed;
So The Windows Mobile OS will send the following messages sequentially;
1.WM_ACTIVATE 's WA_INACTIVE
2.WM_ACTIVATE 's WA_ACTIVE

So whenever the user hits the Home button, the WM_ACTIVATE message with WA_INACTIVE fired.
Steps:
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1.Home Button was pressed ( that indicates WM_ACTIVATE's WA_INACTIVE),Release the video and audio capture filters in WM_ACTIVATE's WA_INACTIVE and
set the boolean variable bInActive as TRUE;
2.When Back button was pressed, The camera application was focused; But it didnt get any message like focus or Activate app or WM_ACTIVATE message;
So what I did was, whenever our camera application got focus, it must paint the camera application window;
So within WM_PAINT message, I will check if bInActive flag was set, then CreateInstance for the video capture filter and audio capture filter and Starts rendering video;