If you are trying to implement tinymce for your theme options page or plugins and the Insert/edit link doesn’t pop up the dialog after the button is clicked, try this:

add_action( 'admin_print_footer_scripts', 'wp_tiny_mce_preload_dialogs', 30 );
add_action( 'tiny_mce_preload_dialogs', 'wp_link_dialog', 30 );

This worked for me as of version 3.1.3.