Bug? in zoom with TkAgg backend


TkAgg backend works fine except a corner case with the zoom button.

Consider with simple code :

from pylab import *
A = rand(1000,1000)

When I zoom 3 or 4 times on the resulting image using the backend zoom button, I get an all white image from a certain zoom level (i.e. from factor of 100).

It is clearly a corner case but I sometime have to zoom on very fine details.

Consider this code in backend_bases.py :

lastx, lasty, a, ind, lim, trans = self._xypress
        # ignore singular clicks - 5 pixels is a threshold
        if abs(x-lastx)<5 or abs(y-lasty)<5:
            self._xypress = None

I think we could decrease the threshold down to 1 pixel. Please tell me if it is incompatible with another piece of code.

Selecting a less than 1*1 (or 2*2) pixels area should do nothing (and not produce a blank image).