This will draw a dot on a locked, 32-bit image.
These are the current mode values:
0 : Replace : Replaces current dot with new dot.
1 : Add : Adds colour of current dot and new dot.
2 : Subtract : Subtracts new dot's colour from old dot.
3 : Average : Averages the current dot with new dot.
4 : Overlay : Overlays new dot on top of old dot. The alpha value will determine
how much of the old dot shows through.
DBIMAGE DOT32 Int ID, dword colour, int x, int y, byte mode