Comment 5 for bug 1407880

Fix should be in menu.css file added to ~/.config/cairo-dock/current_theme

.window-frame {
 border-radius: 7px;
 border-width: 0px;
 margin: 10px;
 box-shadow: 0 0px 0px 0px alpha(black, 0.0);
}

Removing shadows from GtkWindow ( .window.frame ) in GTK theme makes borders of
client side decorated programs invisible on white backgrounds, thus all GTK 3 themes
must use these shadows. Remove them from cairo-dock with the above file

This menu.css file should probably be included by default in cairo-dock, because this shadow
bug is NOT likely to be fixed in GTK3 by GNOME. Using this file removes the shadows from around
cairo-dock dialogs and menus while allowing them to be kept for all other GTK windows