Syscall index: 0x17F7
Function signature: void MsgBoxPush(int lines)
Displays an empty message box centered on the screen and with a blue border.\
int lines - Height of the box in lines (between 1 and 6 inclusive)\
Text or other content must be drawn using methods not provided by this syscall, such as PrintXY. After using MsgBoxPush, you must call MsgBoxPop in order to release the resources allocated by the former.