Strange behaviour when window is highlighted and compositor is active

[giocondo]

When compositor and "Move immediately between windows in an application" are active, the highlighted window is dimmed, making it more difficult to read.

Without compositor all works as expected.

Current behaviour:

Expected behaviour:

Tested on Debian 10 with version 1.24.1 and with the latest version (1.26.0)

[giocondo]

The problem is in compositor-xrender.c in the function window_has_shadow () because there's no rule for the exclusion of the tab_popup window from shading.

This piece of code inside tabpopup.c:

if (meta_prefs_get_compositing_manager ())
{
frame_shadow = GTK_SHADOW_NONE;
gtk_style_context_add_class (gtk_widget_get_style_context (GTK_WIDGET (popup->window)),
GTK_STYLE_CLASS_OSD);
}

doesn't work as expected.