Imagebrowser - use a preset + let admin choose the preset to use.

I would like to be able to configure the dimensions (width/height) of the preview images (imagecache preset) in the browser.
As a suggestion I add a patch. What do you think, does this make sense?

The patch is missing an "imagecache_preset_flush" after changing the settings for width/height.
I tried to implement it in wysiwyg_imageupload_admin_settings_form_submit($form, &$form_state)

/*
 * Implementation of hook_form_submit
 */
function wysiwyg_imageupload_admin_settings_form_submit($form, &$form_state) {
  // If preview width/height changes, flush the imagecache preset
  if ($form_state['values']['wysiwyg_imageupload_browser_preview_width'] != variable_get('wysiwyg_imageupload_browser_preview_width', 200) 
    || $form_state['values']['wysiwyg_imageupload_browser_preview_height'] != variable_get('wysiwyg_imageupload_browser_preview_height', 200) ) {
    imagecache_preset_flush('wysiwyg_imageupload_browser');
    watchdog('info', 'Imagecache preset wysiwyg_imageupload_browser flushed after settings were changed.');
  }
}

For some reason it seems that this is not the correct hook.
Any suggestion where to do this right?