Creating Art for UMG
Establishing a target resolution and scale is important before creating your art assets for UMG.
If you create your assets without a resolution or scale in mind, you may have some textures that are bigger or smaller than they need to be.
In either case you will need to make those assets conform to your UI and that may stretch or skew your textures leading to undesired effects.
As for your textures, try to minimize the amount of built-in padding in the imported texture.
This texture has quite a bit of padding around it making it difficult to get the true size of the window frame.
When using the texture above in a UI screen, if we were to try to rescale it for different screen sizes, the scale will be based on the size of the texture and not the window frame.
If you need to add padding around an object, it�s better to use the padding options inside UMG to provide space around objects so that when you rescale things, they appear the proper scale.
Another issue with this image is the way that the art was created. Rather than one piece of art, this texture could have been split up into pieces (the wood frames separate from the corners and separate from the background).
The corners and wood panel should be their own textures and imperfections make it difficult to tile textures.
Ideally, the corners and wood panel would be their own textures so that you can tile them to make your background image as big/small as you need without stretching the image.
Inside UMG you can set the texture Draw As option to different settings, this would have been a good chance to use the Border mode which supports tiling.