Default background black, not checkerboard?

[SuperbowserX]

Throughout my development of the game, my strategy is this:

1) View, in full-screen, my image in Windows Photo Viewer

2) PrtScrn

3) Paste in Paint as a 1366x768 image, then save

This is how I avoided looking at the checkerboard background that shows up when you have a background image too small. A lot of my backgrounds are of a 1:1.5 (480x720) ratio, and I screenshot those like this so that I can show the actual background in the center of the screen while the rest of it (the black that shows up in the unoccupied area in windows photo viewer) covers up the checkerboarded spot.

But is there any way you can avoid having to do this? Make it black and not chekerboard by default? So that I can put the source 480x720 image straight in there without having to apply a black background over it?

Also, another general question: how can you adjust your game so that it automatically scales down the image to a resolution that fits the target monitor? Can someone in general explain how Ren'py can ensure a suitable desplay for any monitor that may play your game once distributed? And what is the ideal maximum size of images using the new GUI with 1280 x 720 by default?

Sorry if I sound confusing aha. I'm just trying to ask: what exactly does it mean when the new GUI says the resolution is 1280 x 720? I mean I put a 1280 x 776 image in there and it appears just fine. Can someone explain how I am supposed to make my images appear appropriately in Ren'py? How can I manage images that are too large? How can I force Ren'py to fit images larger than the GUI size/user monitor to an appropriate aspect ratio?

[philat]

Checkerboard is only visible while developer mode is true. If you turn it off, it's black.

I don't think there's automatic scaledown. In your example, you'd just see 720 of those 776 pixels. If you scaled that down you'd get black bars on left/right anyway.

[Imperf3kt]

I don't really see the issue for the checkerboard (transparency)
Just do:
show bg black
show your image
with None

Both images will show at the same time, and a black background will sit behind it.
Then, simply never hide bg black.
you might have to define bg black, I just use hex code (image bg black = "#000000")

[SuperbowserX]

Oh okay. Thanks, I didn't know that it would be black off developer mode, that's relieving