Exporting picture with edge

[lmulej]

Dear!

I tried, but it doesn' t work. See examples below. When exporting the red box into .png, I also tried both: "True colour" and "True colour + Alpha". The result was still graphics with white lines on the sides...

Attachments: test3-5.png are the results of exporting.

Is there any other way, to avoid this white white sides?

Kind regards,
Luka