In case you haven't seen it, when you view a particular sale page you can now:

1. Filter what is on sale according to your wishlist

2. Filter to show only those DLCs for the games you already own.

VERY nice GOG. Thank you

Yes, that is known for about a week or two now. Mesa like.

Only games on wishlist + sort by biscount = win.

I need a Filter to change the sales pages back to the old style, the old style which doesn't keep putting up incredibly annoying pop-windows into my face every time I move the cursor.

I thought this thread title was going to be about that, but unfortunately it appears that it isn't and there is still no way to do that.

You can hide the pop-ups with uBlock Origin or similar.

! Pop-ups when hovering over a game thumbnail in the store
gog.com##product-tile-extended-portal

Alternatively, using the userContent.css file in Firefox that requires no add-ons, or the Stylish add-on for multiple browsers:
@-moz-document domain("gog.com") {
product-tile-extended-portal { display: none !important; }
}

Thanks very much for that info.

@OP - Yes these two new options are great, use them every day. BIG THANKS GOG. :)