qwt zoomer: a complete user case scenario?

[fatecasino]

how should i modify the "bode" example in order to implement the following user case scenario?

1. press the zoom button (on)
2. zoom in, several times
3. press the zoom button off( being satisfied with the zooming so far)
4. later I realize that i want to zoom out a bit and press again the zoom button (on)
5. zoom out and press the zoom button (off)
6. open a new data file and plot a new plot (with axis rescaled)
7. repeat steps 1-6 for the new plot
8. end