Receive "function_exists() expects parameter 1 to be string" when saving qwebirc config

When saving qwebirc configuration I always receive the following warning/error (depending if you see it in the GUI or in the log report).

warning: function_exists() expects parameter 1 to be string, array given in /usr/share/drupal6/includes/form.inc on line 765.

But this do not affect the functionality of the admin console as everything is saved correctly.

Fiddling in the code it turns out that it is when assigning the validation function for the width and height fields, that check that they are numeric.

The attached patch solve the issue.

Hope this help
LeTic