"Export as PNG" broken in Firefox 36

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Update to Firefox 36
2. Open Pencil Sketching Firefox add-on
3. Try to "Export as PNG"

What is the expected output? What do you see instead?
The file never appears on the file system.

What version of the product are you using? On what operating system?
I'm using the Firefox addon in Firefox 36, on Windows 7 Professional.

Please provide any additional information below.
-"Export as PNG" works as expected in Firefox 35.0.1.
-This is probably due to the changes Firefox made to addon compatibility 
(https://blog.mozilla.org/addons/2015/01/13/compatibility-for-firefox-36/)
-The workaround is to use the Windows build of Pencil.

Original issue reported on code.google.com by m.overme...@yahoo.ca on 3 Mar 2015 at 1:33

[GoogleCodeExporter]

I fixed this on my fork:
https://github.com/prikhi/pencil

Original comment by Pavan.Ri...@gmail.com on 14 Mar 2015 at 12:08

[GoogleCodeExporter]

You're a hero.

Good timing too, now that Google Code is shutting down.

Original comment by m.overme...@yahoo.ca on 14 Mar 2015 at 2:08