Additional zooming when panning with the mouse drag.

[ivanshuba]

First of all, thank you for the great library!

Now, regarding the issue:
When I'm using the mouse drag for panning the canvas, the end of this operation is accompanied by a small, but noticeable, additional zooming. This happens every time, and even if I simply click on the canvas with the mouse without any dragging - the canvas is slightly zoomed also in that case.

The direction of the 'additional' zoom in both cases is - 'toward the viewer'. I.e. the canvas is getting closer to the viewer.