title: Custom tab size based on file extension
body: <p>To get along better with my coworkers, I have atom configured with 2-space tabs, but in some files, I prefer 4. I'm trying to figure another file type, in this case, my Foo.pro files that are created with Qt Creator.</p>
  <p>I've tried a few dozen things, and nothing seems to work. I'm editing my <code>~/.atom/config.cson</code> and then restarting atom, and there's no change.</p>
  <p>Here's my latest attempt:</p>
  <pre class="lang-coffee prettyprint-override"><code>&quot;*&quot;:
    core:
      customFileTypes:
        &quot;source.pro&quot;: [
          &quot;pro&quot;
        ]
      disabledPackages: [
        &quot;autocomplete-plus&quot;
        &quot;markdown-preview&quot;
        &quot;markdown-preview-plus&quot;
        &quot;spell-check&quot;
      ]
      telemetryConsent: &quot;limited&quot;
      themes: [
        &quot;atom-light-ui&quot;
        &quot;one-light-syntax&quot;
      ]
    editor: {}
    &quot;exception-reporting&quot;:
      userId: &quot;283f523f-3348-4956-97f6-a73675e6e9c6&quot;
    &quot;tree-view&quot;:
      hideVcsIgnoredFiles: true
    welcome:
      showOnStartup: false
  &quot;.basic.html.text&quot;:
    editor:
      tabLength: 4
  &quot;.html.source&quot;:
    editor:
      tabLength: 4
  &quot;.source.pro&quot;:
    editor:
      tabLength: 4
  &quot;.shell.source&quot;:
    editor:
      tabLength: 4
  &quot;.shtml.source&quot;:
    editor:
      tabLength: 4
  </code></pre>
  <p>I'm fairly sure some of these others aren't working, either. Within Atom, if I open my .pro file and do Alt-Cmnd-P, it says the file type is <code>text.plain.null-grammar</code>. And tab width is still 2 characters. So clearly I'm doing something wrong.</p>
  <p>You'll notice I'm attempting to define a custom file type (way at the top) and then define the tab length (near the bottom).</p>