Canvas extra pixels problem

Hello, I have found some weird problem while using canvas.
I have been trying to create 2 boxes (filled and outlined) with FCanvasTileItem and FCanvasLineItem with size 256x16.

But there is a problem, it always creates additional pixels!


Another example:
With FCanvasTileItem I’ve got in-game correct shape with my size 256x16
but with FCanvasLineItem I’ve got in-game wrong sized shape which is 257x17, and I’m 100% sure that it’s because of the additional pixels.

Does anyone know how to solve this problem, I’m trying to create a some pixel art on my UI and these additional pixels make it really hard to make.

P.S. there is FCanvasBoxItem to draw outlined boxes but it’s broken, if you try to draw 256x16 it will return 257x17 with broken corners.

I think I have found another problem, no matter what I try I cannot set alpha channel of FCanvasLineItem at all.