SDL mouse position errors when using SDL_OPENGL with SDL_FULLSCREEN

Hi I am new to newsgroups so I hope its ok to post a question here?

I use sdl 1.2.5 using dev-c++ on windows 2000

If I set the video mode like this

SDL_SetVideoMode( screen_w, screen_h, color_depth, SDL_OPENGL |

The mouse x and y positions are not correct. In full screen the mouse x,y
min and max are still 0,0 to screen_w and screen_h BUT the first time you
move the pointer to the bottom right corner of the screen the mouse x and y
is 476,334. If you continue to move the mouse right and down the x and y
increases until it clips to 599,799. (screen_w and screen_h)

If I set the video mode to SDL_RESIZABLE the mouse positions are fine. If I
remove the SDL_OPENGL flag and use SDL_FULLSCREEN, i get no graphics in my
app but the mouse x and y are correct! So I am sure that my answer lays with
opengl but have no idea how to find the answer.

Is this a known bug, or do I have to do some opengl stuff to get the mouse
to work correctly?

Thanks in advance