$re = '/^.*?(IDC\w*)[\s\S]*?(?:$|(,\n.*$))(\n|$)/mi';
$str = ' LTEXT "Width",IDC_WIDTH_TEXT,203,74,22,10
EDITTEXT IDC_WIDTH_IN,244,73,57,12,ES_AUTOHSCROLL | WS_GROUP
CONTROL "Manually scale instances and paper",IDC_RAD_PSCALE_KEYIN,
"Button",BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP,15,89,132,10
CONTROL "Keep drawing instance scale 1.0",IDC_RAD_PSCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,104,123,10
CONTROL "Keep drawing paper scale 1.0",IDC_RAD_ISCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,119,118,10';
$subst = "$1\n";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php