Truncates the 'pathbar' array up to the specified page at drill-up.
A string value that specifies URL of the page that will be the top-level one in the pathbar. Is NULL by default.
A string value that holds the PHP script (the file name) of the page to be the top-level one in the pathbar. Is NULL by default.
A boolean value which is always true after the 'pathbar' array is rewritten.
The function rewrites its 'pathbar' array so that it becomes truncated up to the element specified by the url and page input parameters. If these parameters are set to NULL, the function uses parameters set for the currently active page.