Remove left and right margin in Poster

Guys, the goal is to have a Poster with an image that has borders. Then I'll use a TextEditBox with that image. But it isn't working. Note that if I create a Poster with this image, a margin of 1px appears on the left and right. Would anyone know how to fix this? The image would have to occupy all the space.

<Poster uri="pkg:/images/input-border.png" />

 

The image is this:

 

 

And the result was this. If you zoom in on the image, you will see that there is a 1px margin on the left and right: