Determines whether the current admin page is generated by a plugin.

Use global $plugin_page and/or get_plugin_page_hookname() hooks.

For more information on this and similar theme functions, check out
the {@link Conditional Tags} article in the Theme Developer Handbook.

function is_plugin_page() {
	_deprecated_function( __FUNCTION__, '3.1.0' );

	global $plugin_page;

	if ( isset($plugin_page) )
		return true;

	return false;
}