--- devel.module	2010-09-23 04:02:06.000000000 +0100
+++ devel.module	2010-09-25 14:35:38.000000000 +0100
@@ -1110,6 +1110,8 @@ function devel_execute_form() {
     '#description' => t('Enter some code. Do not use <code>&lt;?php ?&gt;</code> tags.'),
     '#default_value' => (isset($_SESSION['devel_execute_code']) ? $_SESSION['devel_execute_code'] : ''),
   );
+  // Set the size of the text area to the current number of code lines plus two, with a minimum of five lines.
+  $form['execute']['code']['#rows'] = max(5, substr_count($form['execute']['code']['#default_value'], "\r") + 2);
   $form['execute']['op'] = array('#type' => 'submit', '#value' => t('Execute'));
   $form['#redirect'] = FALSE;
   unset($_SESSION['devel_execute_code']);