title: Atom randomly open files in new window (in stead of in new tab)
body: <p>The issue is that when i allready have a project opened in Atom and i try to open another project (weather i use <code>atom .</code> from the command line or <em>file</em> > <em>Open</em> from the Atom menu) Atom seemingly random opens the project in a new window instead of in a new tab of the current instance.</p>
  
  <p>I'm really getting fed-up with this because i don't want to navigate between three Atom instances to switch between projects. I just want all my projects in one Atom instance and switch between tabs.</p>
  
  <p><em>Sometimes</em> however Atom opens a new project in a new tab of the current instance, but unfortunatly that is the minority.</p>
  
  <p>Does anybody else have this issue or know how i can force Atom to always open a new project in a new tab?</p>
  
  <p>I'm on MacOS 10.13.6 and Atom 1.29.0</p>
  
  <p>Below a screencast of the issue:
  <a href="https://i.stack.imgur.com/BV84U.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BV84U.gif" alt="enter image description here"></a></p>
  
  <p>Since it's pretty hard to see, i justt do <code>atom .</code> from two directories</p>