Function: Whether to display the header text.

Function: Checks whether a header image is set or not.

Function: Checks that the active theme has the required files.

Function: Retrieves all theme modifications.

Function: Retrieves theme modification value for the active theme.

Function: Updates theme modification value for the active theme.

Function: Retrieves template directory path for the active theme.

Function: Retrieves template directory URI for the active theme.

Function: Retrieves theme roots.

Function: Registers a directory that contains themes.