more styling for disabled options

new "Developer" tab (by default all options are disabled, users can't modify them)
fixed UserprefsDisallow export in setup script

prefs_forms.php

@@ -26,6 +26,19 @@ require_once './libraries/user_preferences.inc.php';
 
 $form_display = new FormDisplay();
 foreach ($forms[$form_param] as $form_name => $form) {
+    // skip Developer form if no setting is available
+    if ($form_name == 'Developer') {
+        $show = false;
+        foreach ($form as $field_name) {
+            if (array_search($field_name, $GLOBALS['cfg']['UserprefsDisallow']) === false) {
+                $show = true;
+                break;
+            }
+        }
+        if (!$show) {
+            continue;
+        }
+    }
     $form_display->registerForm($form_name, $form);
 }