Unclear state of "Zoom to fit" button

[simurai]

Prerequisites

• Put an X between the brackets on this line if you have done all of the following:
  • Reproduced the problem in Safe Mode: http://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
  • Followed all applicable steps in the debugging guide: http://flight-manual.atom.io/hacking-atom/sections/debugging/
  • Checked the FAQs on the message board for common solutions: https://discuss.atom.io/c/faq
  • Checked that your issue isn't already filed: https://github.com/issues?utf8=✓&q=is%3Aissue+user%3Aatom
  • Checked that there is not already an Atom package that provides the described functionality: https://atom.io/packages

Description

When "Zoom to fit" is enabled, the button turns blue, which still looks like it can be clicked.

Steps to Reproduce

1. Click "Zoom to fit" button

Expected behavior:

Button should be disabled

Actual behavior: [What actually happens]

Button turns blue

Versions

Atom    : 1.19.0-dev-c78ffa2e8
Electron: 1.6.9
Chrome  : 56.0.2924.87
Node    : 7.4.0

apm  1.18.2
npm  3.10.10
node 6.9.5 x64
python 2.7.10
git 2.12.2

macOS Sierra

Additional Information

Moved over from this comment: #81 (comment)