Rpg Maker Developers Group

(Not sure if this is the right place, as I guess it could fall under a few categories, but I chose this one as I'm unsure if it's possible with JS.)

I recently started working on a Window skin, and this is my selection graphics:
However, in game it looks like this:
As you can see, it works fine on the item screen (as it's formatted for small selections) but it is destroyed in the item category menu. While searching through rpg_windows.js i was unable to find how the selection window is drawn, just that it calls it into memory. Does anyone have an idea of a solution? I though about using a sprite but it sounds like it would be lots of effort for a small detail.

Thanks for reading