The Marque tool is making the empty space in the box remove pixels when i go over other pixels

[Adramalech]

this is what i mean, its only happening on Indexed btw

[Ethan_Buttazzi]

you are using indexed mode, you are basically taking the mask index and shifting around, if you change to rgb mode it will probally work

[dacap]

Hi @Adramalech, probably you have the Opaque option selected:

Try selecting the Transparent one.