1903 small asset missing from MSstyle, i need help to find it!

[TamarindoJuice]

As the title says, some of my themes are missing an small asset on the corner between rows (see the attached image).

I would apreciate to have some word on how to fix it, i use to edit my themes using the WStyle builder...
I don't have much experience and i could not find if it's just a solid color to add to the parameters or a small png file.

Just in case, if anyone here can guide me, what i have to change on the msstyle it will be really thankful!

[Raiderman68]

Same here....Anyone?