Karabiner configuration

private.xml

<?xml version="1.0"?>
<root>
  <item>
    <name>F19 to Escape or Control</name>
    <appendix>(Hold F19 to ctrl, tap F19 to send escape)</appendix>
    <identifier>private.f19_escape_control</identifier>
    <autogen>
      __KeyDownUpToKey__
      KeyCode::F19             <!-- caps-lock sends F19          -->
      __{KeyCode::ESCAPE}__    <!-- send escape when released    -->
      __{KeyCode::CONTROL_L}__ <!-- send ctrl-L when interrupted -->
    </autogen>
  </item>
  <item>
    <name>Control_L to All_The_Things</name>
    <appendix>Control_L to ctrl+cmd+opt</appendix>
    <identifier>private.ctrl_ctrl_cmd_opt</identifier>
    <autogen>
      __KeyOverlaidModifier__
      KeyCode::CONTROL_L,
      KeyCode::CONTROL_L,
      ModifierFlag::COMMAND_L | ModifierFlag::OPTION_L
    </autogen>
  </item>
</root>