Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.440
diff -u -p -r1.440 system.module
--- modules/system/system.module	11 Jan 2007 03:32:56 -0000	1.440
+++ modules/system/system.module	14 Jan 2007 05:16:33 -0000
@@ -747,7 +747,8 @@ function system_image_toolkit_settings()
       '#type' => 'radios',
       '#title' => t('Select an image processing toolkit'),
       '#default_value' => variable_get('image_toolkit', image_get_toolkit()),
-      '#options' => $toolkits_available
+      '#options' => $toolkits_available,
+      '#validate' => array('image_toolkit_validate' => array('image_toolkit', 'image_toolkit')),
     );
   }
   else {
Index: includes/image.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/image.inc,v
retrieving revision 1.17
diff -u -p -r1.17 image.inc
--- includes/image.inc	26 Dec 2006 14:01:41 -0000	1.17
+++ includes/image.inc	14 Jan 2007 05:16:36 -0000
@@ -44,6 +44,15 @@ function image_get_toolkit() {
 }
 
 /**
+ * Validates toolkit selection.
+ */
+function image_toolkit_validate($formelement, $fieldname) {
+  if ($formelement['#value'] == 'gd' && image_gd_check_settings() == false) {
+    form_set_error('image_toolkit', t('The built-in GD image toolkit requires that the GD module for PHP be installed and configured properly. For more information see !url.', array('!url' => l('http://php.net/image', 'http://php.net/image'))));
+  }
+}
+
+/**
  * Invokes the given method using the currently selected toolkit.
  *
  * @param $method A string containing the method to invoke.
@@ -197,8 +206,7 @@ function image_gd_settings() {
     return $form;
   }
   else {
-    form_set_error('image_toolkit', t('The built-in GD image toolkit requires that the GD module for PHP be installed and configured properly. For more information see <a href="@url">PHP\'s image documentation</a>.', array('@url' => 'http://php.net/image')));
-    return FALSE;
+    return array('#type' => 'item', '#value' => t('The built-in GD image toolkit requires that the GD module for PHP be installed and configured properly. For more information see !url.', array('!url' => l('http://php.net/image', 'http://php.net/image'))));
   }
 }