title: How to store the value of a button press?
body: <p>For example I want to store the value of a button press into a variable, so I can have a single proc for all three buttons and perform operations specific to each variable value without code duplication.</p>
  
  <pre><code>button .buttonRed -text "Red" -command "popUpColor"
  button .buttonBlue -text "Blue" -command "popUpColor" 
  button .buttonGreen -text "green" -command "popUpColor"
  </code></pre>