title: How to use msgbox in R
body: <p>How can I display a message box in <code>R</code> ?</p>
  
  <p>I'm looking for something similar to <code>msgbox</code> in VBA, so I can for example alert the user about a problem.</p>
  
  <p>Additionally I would like to allow some user interaction. So for example I could ask the user what day the program should use.</p>