I started using matblotlib few days ago, and like it.
I encountered the following problem:

I have a figure with two subplots. I use the toolbar for going back and forth after changing axes' scales. I want to change something in the graphs from time to time  -- like shifting some lines elsewhere (by editing lines' properties). By playing with this I found a strange behaviour of the axes() command:

I thought that calling simple axes('existing axes instance') should only make the 'existing axes instance' current. But, at least for me, this command also resets the possibility of using back & forward buttons. Is this really wanted?

What I truly want to achieve is to be able to use those navigation buttons independently on what is drawn in the axes -- only taking care of the scales. I use the first subplot for visualizing input data, the second subplot for visualizing fft of the input data. I have two additional vertical lines in the former plot for selecting the range of the input data to be then passed to fft. I want to be able to change scales of both graphs at any time and do not discontinue this ability by adding new things to the graphs...

1) is the described behaviour of axes() function intended?
2) what events have some influence on navigation buttons?
3) what shall I read in order to be able to exercise some control over the buttons?

Thank you a lot! :)
Ruda Sykora