I'm having an issue finding a specific section to edit in SkinStudio. I am using the Diamond skin in WindowBlinds 11 with a Windows 10 file explorer. Specifically, I want to edit the background texture of the following dropdown menu in File Explorer:

It appears when I click the button that says "Include selected folder in library" in the command bar. I cannot find it anywhere in SkinStudio and it's driving me mad.
It seems that the above menu uses a different texture from the regular pop-up menu (example below, notice it doesn't have a blueish hue like above):

If anyone can help me out on this it would be greatly appreciated. Thanks!