Use default theme for panel preview page

Being able to preview a panel prior to save is a great feature.

However the current preview uses the backend admin theme so doesn't accurately reflect the look of the panel on the frontend.

I wanted to set the theme to the frontend theme for the preview page.

I tried using hook_custom_theme but that gets overridden by panels or some other module later.

So, I ended up using the second recommended approach of hook_menu_alter which is working nicely.

Just thought I'd share in case anyone else was looking for this.

I'm not sure how this would fit into a patch, but is useful nonetheless.

<?php
/**
 * hook_menu_alter
 */
function example_menu_alter(&$items){
  // Add own theme callback to panels admin page for override
  $items['admin/structure/pages/%ctools_js/operation/%page_manager_cache']['theme callback'] = 'example_preview_theme';
}

/**
 * Custom theme callback for panels preview
 */
function example_preview_theme(){
  $args = arg();
  // If last URL argument is preview, then set frontend default theme
  if( array_pop($args) == 'preview' ){
    return variable_get('theme_default', 'bartik');
  }
}
?>

Thanks again for the awesome module,

DT