Wrong CSS file being used

I checked the values of the global variables $theme, $theme_key, $custom_theme; the first two variables seem to be set to an empty string, and the last one is set to zero.

That is strange, as Drupal is showing the correct theme.

It seems that if the user has set a theme for himself, those variables get a not usable value; in this case, the theme used is the one reported by $user->theme, where $user is the global variable associated with the current user object.

I got it to work by changing the function activemenu_theme_css() to be:

function activemenu_theme_css() {
  global $custom_theme, $theme, $user;
  
  if (isset($user->theme) && $user->theme != '') {
    $current_theme = $user->theme;
  }
  elseif (!empty($custom_theme)) {
    $current_theme = $custom_theme;
  }
  else {
    $current_theme = $theme ? $theme : variable_get('theme_default', 'garland');
  }
  
  $path = drupal_get_path('module', 'activemenu');
  $file = $path .'/theme/'. $current_theme .'.css';
  if (file_exists($file)) {
    drupal_add_css($file);
  }
  else {
    drupal_add_css($path .'/activemenu.css', 'theme');
  }
}

I forgot to say I am using Drupal 6.3.

Now I got it to use the right CSS file if the user has set his own theme, and I also fixed a problem in the visualization of the navigation menu which had the plus (and minus) images placed over the menu titles. I am not able to make the Zen Classic use the plus, and minus images (the theme uses its own images for the menus).

The module is also using the wrong CSS file in pages like admin/build/block/list/<theme> (when <theme> is not the site theme).
The issue seems caused by $theme, $theme_key, $custom_theme not getting any useful value if init_theme() is not called before to check their values.
init_theme() cannot be called in pages like admin/build/block/list/<theme>, or it would force the page to be rendered using the site theme (which is not the wanted thing).

The problem is present also in Drupal 6.4.

As also reported by a comment in the jstools.module referred to the function jstools_theme_include():

To avoid having to prematurely initialize the theme, call this function from a hook_footer() implementation. hook_footer() typically is called after the theme has been initiated, but before the header has been generated.

Inside the implementation of hook_footer() the variables $theme, $theme_key, $custom_theme get a useful value.

Did anybody else notice that in some themes the [+], and [-] are placed to the left of the imagine used by the theme for the <li> tags?