QuickTime 4 Reference

Adding a Custom Button

Your application can request a custom button in a movie controller by setting the mcFlagsUseCustomButton flag in the movie controller flags. The appearance of this button is determined by the movie controller. In the movie controller provided with QuickTime, this button is a downward-pointing arrow, and it is recommended that other movie controllers use a downward-pointing arrow for their custom buttons.

When its custom button is clicked, the movie controller generates the mcActionCustomButtonClick action. Your application responds by checking for the mcActionCustomButtonClick action in its action filter function and performing any tasks that are necessary.