Add Icon to your CType

When your extension adds a new CType, use 3rd parameter to add the icon for the type select.

t3lib_extMgm::addPlugin(
  array(
    'LLL:EXT:yourext/locallang_db.xml:tt_content.CType_pi1',
    $_EXTKEY.'_pi1',
    t3lib_extMgm::extRelPath($_EXTKEY).'ext_icon.gif'
  ),
  'CType'
);