Clicking the fullscreen button steals keyboard focus away from the canvas

[ferdnyc]

When the output canvas has keyboard focus, the shortcuts documented in the popup dialog work:

For instance, I can repeatedly type f to cycle in and out of fullscreen mode.

However, if I click the fullscreen icon (whether entering or leaving fullscreen mode), the f shortcut stops working until I click on the canvas again to reapply keyboard focus.

[ferdnyc]

To reproduce

1. click on the SVG canvas
2. type f to enter fullscreen
3. type f again to exit fullscreen
4. click the opposing-arrows icon in the upper right corner of the canvas to re-enter fullscreen
5. type f again, and see that nothing happens
6. click somewhere on the canvas
7. type f again to exit fullscreen