Where can you find Default Values for Cursor Hotspots? [closed]

GUI toolkits like fltk allow you set a custom cursor for your app. When setting a custom cursor image, they also ask for a "hotspot":

void Fl_Window::cursor(const Fl_RGB_Image *image,int hotx, int hoty)    

Changes the cursor for this window.

This always calls the system, if you are changing the cursor a lot you may want to keep track of how you set it in a static variable and call this only if the new cursor is different.

The default cursor will be used if the provided image cannot be used as a cursor.

Does anyone know where you can find the typical hot spot values for OS cursors?