For those people who need to quickly/temporarily switch the focus to manual, check the page 120 of the manual (page 122 of the PDF file http://www.pentaximaging.com/files/manual/istDS_repl_061405_web.pdf ) This is a bit obscure capability (if you did not read the manual).
Regarding the original question: When the camera is not set to the "auto pict" or any of the "action" modes, but to P, T, A, M, B (and "flash off") modes, then even if the flash is set to "automatic discharge", and the built-in flash is down (closed), it will not pop-up automatically and the camera will not refuse to fire. Igor

