Syscall index: 0x02C7
Function signature: void HourGlass(void)
Directly draws the busy-indicator in the upper right corner. The indicator will automatically spin as this syscall is called more times, but please note that it doesn't spin every time the syscall is called - the OS seems to check the RTC to see if enough time has passed for another spin.
Most Bfile syscalls automatically show the busy-indicator when operating.