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Say like.. I'm going to change every window in the game background color to white, and I want the border thicker plus its color to red. Which part in the RGSS should I edit and where can I find it?
I actually just started a tutorial that answers a bunch of common questions here. Check out the Titles, Tilesets, Windowskins, etc. section. I believe that's what you're looking for.
Top: The border. Not sure what the arrows are.
Middle-Left: The menu coursor (Can't spell it right.).
Middle-Right: Those appear in battle when it's your turn.
Bottom: Target coursor.