Here is some code copy for the SDK doc.

Code:
// create the bitmap utils
TBitmapUtil bitmap1Util(iBitmap1);
TBitmapUtil bitmap4Util(iBitmap4);

// Begin manipulation with bitmap1Util, setting initial pixel to 0,0 
bitmap1Util.Begin(TPoint(0,0)); 
// Begin manipulation with bitmap4Util, setting initial pixel to 0,0
bitmap4Util.Begin(TPoint(0,0),bitmap1Util); 

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.
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// each Begin() must have a corresponding End()
bitmap1Util.End();
bitmap4Util.End();
And my question is about the function call:
bitmap4Util.Begin(TPoint(0,0),bitmap1Util);

I guess I did hit a problem that if I write this line as:
bitmap4Util.Begin(TPoint(0,0));

The app will freeze up, so, can anyone please tell me what is the begin function really doing? It lock up the heap of the BMP allocate to the TBitmapUtil, or it lock the heap for all the BMP?

Thanks in Advance