title: How to view the source code of a method in a standard library of Racket?
body: <p>For example, there is a <a href="http://docs.racket-lang.org/gui/editor-canvas_.html?q=append-editor-operatio#%28meth._%28%28%28lib._mred%2Fmain..rkt%29._editor-canvas~25%29._on-char%29%29" rel="noreferrer">on-char</a> method on the <code>editor-canvas%</code> class in <code>racket/gui/base</code>. It handles the <code>'wheel-up</code> and <code>'wheel-down</code> events and passes other events to the <a href="http://docs.racket-lang.org/gui/canvas___.html?q=canvas%25#%28meth._%28%28%28lib._mred%2Fmain..rkt%29._canvas~3c~25~3e%29._on-char%29%29" rel="noreferrer">on-char</a> method on <code>canvas%</code>.</p>
  
  <p>I would like to view the source code and see how it does that.</p>
  
  <p>I wish there are some tools like the <a href="http://ruby-doc.org/core-2.2.0/Array.html#method-i-each" rel="noreferrer">Ruby API documentation</a>, but now I do not even know where the source code of <code>racket/gui/base</code> is.</p>
  
  <p><img src="https://i.stack.imgur.com/uOZPg.png" alt="Array#each"></p>