title: Skip installation in Inno Setup if other program is not installed
body: <p>I have to find way how to skip installation if other program is not installed. I can detect registry of other program (basic script returns true/false), it is not problem. But I don't know how to skip installation.</p>
  <p>In short: if one key in registry is not set, print message <em>'instal program xyz before this one'</em> and finish installator.</p>