Suppress warnings created by certain plugins and themes in WordPress.

warnings.php

/**
 * Suppress errors generated by specified WordPress plugins.
 *
 * Put this in /wp-content/mu-plugins/
 *
 * @param string $errno The error number.
 * @param string $errstr The error message.
 * @param string $errfile Path to the file that caused the error.
 * @param int $errline Line number of the error.
 * @return bool True to suppress error reporting; false to use default error handler.
 */
function my_error_handler( $errno, $errstr, $errfile, $errline ) {
	if ( E_STRICT == $errno ) {
		// Return true to disable all strict notices.
		//return true;
	}

	// Do not display these notices:
	$patterns = array(
		'themes/cbox-theme',
		'Group_Extension::display', // older BP group extensions
		'bp_setup_current_user was called', // annoying bp_setup_current_user notices
	);

	foreach ( $patterns as $pattern ) {
		$pattern = str_replace( array( '/', '\\' ), DIRECTORY_SEPARATOR, $pattern );

		if ( false !== strpos( $errstr, $pattern ) ) {
			return true;
		}

		if ( false !== strpos( $errfile, $pattern ) ) {
			return true;
		}
	}

	// The path was not found, so report the error.
	return false;
}
set_error_handler( 'my_error_handler' );