CodeMirror 2: Search/Replace Demo

<dt id="option_indentWithTabs"><code>indentWithTabs (boolean)</code></dt>
  <dd>Whether, when indenting, the first N*8 spaces should be
  replaced by N tabs. Default is false.</dd>

<dt id="option_tabMode"><code>tabMode (string)</code></dt>
  <dd>Determines what happens when the user presses the tab key.
  Must be one of the following:
    <dl>
      <dt><code>"classic" (the default)</code></dt>
      <dd>When nothing is selected, insert a tab. Otherwise,
      behave like the <code>"shift"</code> mode. (When shift is
      held, this behaves like the <code>"indent"</code> mode.)</dd>
      <dt><code>"shift"</code></dt>
      <dd>Indent all selected lines by
      one <a href="#option_indentUnit"><code>indentUnit</code></a>.
      If shift was held while pressing tab, un-indent all selected
      lines one unit.</dd>
      <dt><code>"indent"</code></dt>
      <dd>Indent the line the 'correctly', based on its syntactic
      context. Only works if the
      mode <a href="#indent">supports</a> it.</dd>
      <dt><code>"default"</code></dt>
      <dd>Do not capture tab presses, let the browser apply its
      default behaviour (which usually means it skips to the next
      control).</dd>
    </dl></dd>

<dt id="option_enterMode"><code>enterMode (string)</code></dt>
  <dd>Determines whether and how new lines are indented when the
  enter key is pressed. The following modes are supported:
    <dl>
      <dt><code>"indent" (the default)</code></dt>
      <dd>Use the mode's indentation rules to give the new line
      the correct indentation.</dd>
      <dt><code>"keep"</code></dt>
      <dd>Indent the line the same as the previous line.</dd>
      <dt><code>"flat"</code></dt>
      <dd>Do not indent the new line.</dd>
    </dl></dd>

or it by

Demonstration of search/replace functionality and marking text.