title: "Design" button grayed out in Qt Creator for QML Project
body: <p>I'm on a Kubuntu 11 system and trying out my first Qt Quick project.  As this is Kubuntu I'm just running with the Qt that came with it, which has worked fine so far.</p>
  
  <p>I asked Qt Creator to create the sample "Hello World" project from Qt Quick.  But the design button was grayed out, as were the run buttons.</p>
  
  <p>At first when I went into the Projects menu under "Run Settings" it said <em>Qt version: [Invalid Qt Version]</em>.  Pushing the "Manage Qt versions" button brings up a tree control that looks like this:</p>
  
  <pre><code>v -- Auto-detected
  |     |
  |     +---Qt in PATH /usr/bin/qmake-qt4
  |
  +--- Manual
  </code></pre>
  
  <p>At the bottom of the dialog it says <em>"Found Qt version 4.7.2, using mkspec linux-g++ (Desktop)"</em></p>
  
  <p>I found out that I could get the "Invalid Qt version" message to go away by manually choosing to <a href="http://ubuntuforums.org/showthread.php?p=11144183" rel="noreferrer">install QmlViewer from the app repositories</a>.  You'd think it would say something more like <em>"Qml Viewer not found, please install it"</em> but...oh well.  Now it says <em>Qt Version: [Qt in PATH]</em>.</p>
  
  <p>So that's fixed, and the Qml app runs.  But the "Design" button is still grayed out.  Qt Designer is installed as an application, and its plugin shows in the "About Plugins..." list.  The design button is enabled in ordinary (non-Qt-Quick) projects when I click on a form file, just not for .qml files.</p>