Avid was super lazy when they rolled out the Windows versions and didn't bother to stylize any of the system level stuff like file menus and child windows, which sucks but luckily since they were that lazy you can change these more directly using custom windows themes if they address these assets.
you will need
UXThemePatcher and a custom theme. The only one I know of that does this is this one
Matte by KDr3w as I asked him if he would go in and do that and he graciously agreed.
I'm also going to be digging into custom .msstyles at some point so hopefully we'll get a few more options going. Tbh I hope they don't fix it because this looks way better than what Avid would do.