struct Window
{
  int hwnd = 0;
  void (*callback)(int, int, int, int, int);
  int hwnd_parent = 0;
  int layout_mode = 0;
  bool placeholder = false;
};

#define LAYOUT_MODE_NONE             0
#define LAYOUT_MODE_SPLIT_VERTICAL   1
#define LAYOUT_MODE_SPLIT_HORIZONTAL 2
#define LAYOUT_MODE_SPLIT_AUTO       3

#define ROTATION_VERTICAL_BUTTON_UP        0
#define ROTATION_HORIZONTAL_BUTTON_RIGHT   1
#define ROTATION_VERTICAL_BUTTON_DOWN      2
#define ROTATION_HORIZONTAL_BUTTON_LEFT    3

int UI(int pid, unsigned int signal);
int UI_create_window(void (*callback)(int, int, int, int, int), int parent = 0, int zorder = 0);
int UI_create_window(int parent = 0, int zorder = 0);
void UI_set_layout_mode(int hwnd, int layout_mode);