Added a GTK3 CSS font provider helper and updated emoji font application to avoid deprecated override APIs in GTK3 builds.

Switched GTK3 setup color previews, entry styling, and user list palette updates to use gtkutil_apply_palette instead of deprecated GTK3 overrides.

src/fe-gtk/maingui.c

@@ -117,6 +117,44 @@ mg_color_component_to_pango (double value)
 	return (guint16)(value * 65535.0 + 0.5);
 }
 
+#if HAVE_GTK3
+static void
+mg_apply_font_css (GtkWidget *widget, const PangoFontDescription *desc,
+				   const char *class_name, const char *provider_key)
+{
+	GtkStyleContext *context;
+	GtkCssProvider *provider;
+	char *font_str;
+	GString *css;
+
+	if (!widget || !desc)
+		return;
+
+	context = gtk_widget_get_style_context (widget);
+	if (!context)
+		return;
+
+	provider = g_object_get_data (G_OBJECT (widget), provider_key);
+	if (!provider)
+	{
+		provider = gtk_css_provider_new ();
+		g_object_set_data_full (G_OBJECT (widget), provider_key, provider, g_object_unref);
+	}
+
+	font_str = pango_font_description_to_string (desc);
+	css = g_string_new (".");
+	g_string_append (css, class_name);
+	g_string_append_printf (css, " { font: %s; }", font_str);
+	gtk_css_provider_load_from_data (provider, css->str, -1, NULL);
+	g_string_free (css, TRUE);
+	g_free (font_str);
+
+	gtk_style_context_add_class (context, class_name);
+	gtk_style_context_add_provider (context, GTK_STYLE_PROVIDER (provider),
+	                                GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+}
+#endif
+
 static void
 mg_set_label_alignment_start (GtkWidget *widget)
 {
@@ -3243,7 +3281,8 @@ mg_apply_emoji_fallback_widget (GtkWidget *widget)
                 return;
 
 #if HAVE_GTK3
-        gtk_widget_override_font (widget, desc);
+		mg_apply_font_css (widget, desc, "zoitechat-emoji-font",
+		                   "zoitechat-emoji-font-provider");
 #else
         gtk_widget_modify_font (widget, desc);
 #endif
@@ -3285,7 +3324,8 @@ mg_apply_emoji_primary_widget (GtkWidget *widget)
                 return;
 
 #if HAVE_GTK3
-        gtk_widget_override_font (widget, desc);
+		mg_apply_font_css (widget, desc, "zoitechat-emoji-font",
+		                   "zoitechat-emoji-font-provider");
 #else
         gtk_widget_modify_font (widget, desc);
 #endif

src/fe-gtk/setup.c

@@ -1692,15 +1692,7 @@ setup_color_button_apply (GtkWidget *button, const PaletteColor *color)
 {
 	GtkWidget *target = g_object_get_data (G_OBJECT (button), "zoitechat-color-box");
 	GtkWidget *apply_widget = GTK_IS_WIDGET (target) ? target : button;
-#if HAVE_GTK3
-	GtkStateFlags states[] = {
-		GTK_STATE_FLAG_NORMAL,
-		GTK_STATE_FLAG_PRELIGHT,
-		GTK_STATE_FLAG_ACTIVE,
-		GTK_STATE_FLAG_SELECTED,
-		GTK_STATE_FLAG_INSENSITIVE
-	};
-#else
+#if !HAVE_GTK3
 	GtkStateType states[] = {
 		GTK_STATE_NORMAL,
 		GTK_STATE_PRELIGHT,
@@ -1711,18 +1703,18 @@ setup_color_button_apply (GtkWidget *button, const PaletteColor *color)
 #endif
 	guint i;
 
-	for (i = 0; i < G_N_ELEMENTS (states); i++)
 #if HAVE_GTK3
-		gtk_widget_override_background_color (apply_widget, states[i], color);
+	gtkutil_apply_palette (apply_widget, color, NULL, NULL);
 #else
+	for (i = 0; i < G_N_ELEMENTS (states); i++)
 		gtk_widget_modify_bg (apply_widget, states[i], color);
 #endif
 
 	if (apply_widget != button)
-		for (i = 0; i < G_N_ELEMENTS (states); i++)
 #if HAVE_GTK3
-			gtk_widget_override_background_color (button, states[i], color);
+		gtkutil_apply_palette (button, color, NULL, NULL);
 #else
+		for (i = 0; i < G_N_ELEMENTS (states); i++)
 			gtk_widget_modify_bg (button, states[i], color);
 #endif
 
@@ -2803,9 +2795,8 @@ static void
 setup_apply_entry_style (GtkWidget *entry)
 {
 #if HAVE_GTK3
-        gtk_widget_override_background_color (entry, GTK_STATE_FLAG_NORMAL, &colors[COL_BG]);
-        gtk_widget_override_color (entry, GTK_STATE_FLAG_NORMAL, &colors[COL_FG]);
-        gtk_widget_override_font (entry, input_style->font_desc);
+        gtkutil_apply_palette (entry, &colors[COL_BG], &colors[COL_FG],
+                               input_style->font_desc);
 #else
         gtk_widget_modify_base (entry, GTK_STATE_NORMAL, &colors[COL_BG]);
         gtk_widget_modify_text (entry, GTK_STATE_NORMAL, &colors[COL_FG]);
@@ -2819,29 +2810,26 @@ setup_apply_to_sess (session_gui *gui)
         mg_update_xtext (gui->xtext);
         chanview_apply_theme ((chanview *) gui->chanview);
 
-        if (prefs.hex_gui_ulist_style)
-        {
-#if HAVE_GTK3
-                gtk_widget_override_font (gui->user_tree, input_style->font_desc);
-#else
-                gtk_widget_modify_font (gui->user_tree, input_style->font_desc);
+#if !HAVE_GTK3
+	if (prefs.hex_gui_ulist_style)
+		gtk_widget_modify_font (gui->user_tree, input_style->font_desc);
 #endif
-        }
 
 #if HAVE_GTK3
-        if (prefs.hex_gui_ulist_style || fe_dark_mode_is_enabled ())
 	{
-		gtk_widget_override_background_color (gui->user_tree, GTK_STATE_FLAG_NORMAL, &colors[COL_BG]);
+		const PaletteColor *bg = NULL;
+		const PaletteColor *fg = NULL;
+		const PangoFontDescription *font = NULL;
+
+		if (prefs.hex_gui_ulist_style || fe_dark_mode_is_enabled ())
+			bg = &colors[COL_BG];
 		if (fe_dark_mode_is_enabled ())
-			gtk_widget_override_color (gui->user_tree, GTK_STATE_FLAG_NORMAL, &colors[COL_FG]);
-		else
-			gtk_widget_override_color (gui->user_tree, GTK_STATE_FLAG_NORMAL, NULL);
-        }
-        else
-        {
-                gtk_widget_override_background_color (gui->user_tree, GTK_STATE_FLAG_NORMAL, NULL);
-                gtk_widget_override_color (gui->user_tree, GTK_STATE_FLAG_NORMAL, NULL);
-        }
+			fg = &colors[COL_FG];
+		if (prefs.hex_gui_ulist_style)
+			font = input_style->font_desc;
+
+		gtkutil_apply_palette (gui->user_tree, bg, fg, font);
+	}
 #else
         if (prefs.hex_gui_ulist_style || fe_dark_mode_is_enabled ())
 	{