title: Intellij Idea not building when I press Run
body: <p>I have a simple hello world project in Kotlin, running in Intellij Idea. I can build and run it just fine, but if I make changes, save and press the green run button (or <kbd>Shift</kbd>+<kbd>F10</kbd>), Intellij runs the old version of the file, before I made the changes. I can fix this by first Building the project (<kbd>Ctrl</kbd>+<kbd>F9</kbd>), then running it (<kbd>Shift</kbd>+<kbd>F10</kbd>). Why is this? Must I always build first, then run? Why doesn't Run build the project for me?</p>
  
  <p>Here is my code, though I'm sure that's not the problem:</p>
  
  <pre><code>fun main(args: Array&lt;String&gt;) {
      println("hello world")
  }
  </code></pre>