I am now on the little rescue boat. I cannot seem to see a "O" in order to progress my gameplay.

I am unable to move my mouse pointer beyond some invisible limiting "square" where the pointer is unable to search.
Should I window the game? I just cannot see how that might help. I might just try it but that might not even function for the game.
Exiting the full screen option doesn't help; changing mouse speed doesn't help; nor does changing camera sensitivity.
Any suggestions? I realize that this game is free but still would like to progress.

Thanks in advance...

I finally decided to click on the sun. Okay, progression and game continues.