-top => NUMBER Specifies the top position (Y coordinate) for the window, in pixels. For Windows and DialogBoxes is absolute (screen position), while for controls is relative to the client area of their parent window. So what I don't understand is how moving the top or left hand side of the Label control (that has the bitmap attached and is not actually anchored to a specific part of the main window or is it) causes the image to scroll ?????

As far as can tell, in this line:$self->BM->Top( -$new_pos ); is telling the label (a client window, thus relative positioning) containing the bitmap, which part of the bitmap to display.

If you move the vertical scrollbar down 3 units, it needs to reposition the top of the bitmap -3 units above the top of the label client area, thus hiding those top 3 units worth of bitmap.

Does that make things any clearer?

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In reply to Re^3: Win32 GUI scrolling controls within the main window by BrowserUk
in thread Win32 GUI scrolling controls within the main window by SteveR

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