Horizontal and vertical scrolling not working on Linux

[Juan Pablo Caram]

Holding shift and control while scrolling should scroll horizontally and vertically but is zooming, which is the default behavior without a key being pressed.

[Juan Pablo Caram]

There might be some interaction with issue #95.

[Juan Pablo Caram]

See https://github.com/matplotlib/matplotlib/issues/707/

It suggests:

self.canvas.setFocusPolicy( Qt.ClickFocus )
self.canvas.setFocus()

right after self.canvas is attached to it's parent.

This doesn't seem to be the problem as FlatCAMDraw is properly responding to key_press.

[Juan Pablo Caram]

Was caused by issue #95. Solved in commit 4cbeec5.