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?