You can use a constant of type ThemeArrowOrientation in the function DrawThemePopupArrow to specify the direction in which a pop-up arrow is drawn on a button. The ThemeArrowOrientation constants are available with Appearance Manager 1.1 and later.
enum {
kThemeArrowLeft = 0,
kThemeArrowDown = 1,
kThemeArrowRight= 2,
kThemeArrowUp = 3
};
typedef UInt16 ThemeArrowOrientation;