Avoid Vibrancy in Mojave

Hello Everyone,

I have an app where I have a few NSPopover everything works fine before Mojave but in that version 10.14 all objets inside NSPopover are transparent, is there a way I can avoid this?

I tried
if (NSProcessInfo.ProcessInfo.OperatingSystemVersion.Major == 10 &&
NSProcessInfo.ProcessInfo.OperatingSystemVersion.Minor == 14)
{
Debug.WriteLine("We are in mojave");
NSApplication.SharedApplication.Appearance = (NSAppearance.GetAppearance(NSAppearance.NameAqua));
}

Sometimes it work and other don't, even NSAlerts have these issues too, also tried to apply a Layer (WantsLayer=true and a color to that layer)

Is there a better way to do this?