Clears a pixbuf to the given RGBA value, converting the RGBA value into the pixbuf's pixel format.
The alpha component will be ignored if the pixbuf doesn't have an alpha channel.
RGBA pixel to used to clear (0xffffffff is opaque white, 0x00000000 transparent black)
Clears a pixbuf to the given RGBA value, converting the RGBA value into the pixbuf's pixel format.
The alpha component will be ignored if the pixbuf doesn't have an alpha channel.