Changing Spectrogram range dynamically

Hi,

I'd like to know what is the proper way of doing this (changing x range, y range, color range)
dynamically... at the press of a button...

I do have it working, but I'm afraid in a much too complicated way...

I' m following closely the spectrogram example...

So I have a DataInterface class, deriving from QwtRasterData...
it has methods to update the bounding rect and the range...

when I call these methods, and then use replot()
nothing happens...

I need to use setData() method of QwtSpectrogram again
and then replot()

Where I am confused is that, then the copy() function is called...
and I will end up with multiple copies of the same DataInferface object, isn't it?