Unable to change alignment attached to a button

[stalniy]

I have this markup:

<div #toolbar>
  <span class="btn-group">
    <button type="button" class="ql-align btn" value=""></button>
    <button type="button" class="ql-align btn" value="center"></button>
  </span>
</div>
<div #editorPlaceholder></div>

When I click on first button I want alignment to be left.

Steps for Reproduction

1. Visit http://jsfiddle.net/8k81cojh/1/
2. type some text inside editor
3. Click on "center" button
4. Click on "left" button

Expected behavior: [expected]
text is aligned to the left

Actual behavior: [actual]
text is centered

Platforms: [ex. Chrome 48 on Mac 10.11]
Chrome 51.0.2704.103 Mac 10+

Version: [version]
beta.9

[stalniy]

the issue is in https://github.com/quilljs/quill/blob/develop/modules/toolbar.js#L87
there is no way to pass false as a button value