about rounded UI and StyleBoxFlat

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:bust_in_silhouette: Asked By airs1991

I used StyleBoxFlat to draw a rounded rectangle.

But when I use the Corner Radius property, the inside of the border is square, while the outside of the rectangle is round.

So in the corner, they are missing a piece. As long as the border is thick enough, it is obvious.

(It is encountered when using ProgressBar, other components have no problem.)