Added a GTK3-specific vertical separator in the channel list while keeping the GTK2 separator for non-GTK3 builds, preserving packing and visibility behavior.

Updated the horizontal tab separator creation to use GTK3’s vertical separator API with a GTK2 fallback, keeping the same packing and show logic.

src/fe-gtk/chanlist.c

@@ -1157,7 +1157,11 @@ chanlist_opengui (server *serv, int do_refresh)
 
 	/* ============================================================= */
 
+#if HAVE_GTK3
+	wid = gtk_separator_new (GTK_ORIENTATION_VERTICAL);
+#else
 	wid = gtk_vseparator_new ();
+#endif
 #if HAVE_GTK3
 	chanlist_grid_attach (table, wid, 2, 0, 1, 5, FALSE, FALSE,
 						  GTK_ALIGN_FILL, GTK_ALIGN_FILL);

src/fe-gtk/chanview-tabs.c

@@ -539,7 +539,11 @@ tab_add_real (chanview *cv, GtkWidget *tab, chan *ch)
 #elif !HAVE_GTK3
 		box = gtk_hbox_new (FALSE, 0);
 #endif
+#if HAVE_GTK3
+		sep = gtk_separator_new (GTK_ORIENTATION_VERTICAL);
+#elif !HAVE_GTK3
 		sep = gtk_vseparator_new ();
+#endif
 	}
 
 	gtk_box_pack_end (GTK_BOX (box), sep, 0, 0, 4);