background_showcolour
Returns: Boolean
When in a room, it can have no background image selected for any of its background_index, in which case you should set a background colour with
the background_colour variable and make sure that it is visible by setting this variable is set to true. Having a room with no background
image and no background colour will result in graphical artefacts being drawn on the screen and is not recommended.
if background_index[0] == -1
{
background_colour = c_black;
background_showcolour = true;
}
The above code checks to see if background0 has an image assigned to it and if not it sets the background colour to black and flags it to be shown.