Consolidated GTK3 vs GTK2 icon macro guards in the channel list UI to keep named icons on GTK3 and stock icons on GTK2 behind a single conditional block.

Aligned plugin UI icon macros with the same GTK3/GTK2 conditional pattern for named icons vs stock icons.
Ensured GTK3 popup helper usage and clarified GTK3/GTK2 icon macro selection in the main menu handling code.

src/fe-gtk/chanlist.c

@@ -51,8 +51,7 @@
 #define ICON_CHANLIST_FIND "edit-find"
 #define ICON_CHANLIST_REFRESH "view-refresh"
 #define ICON_CHANLIST_SAVE "document-save-as"
-#endif
-#if !HAVE_GTK3
+#else
 #define ICON_CHANLIST_JOIN GTK_STOCK_JUMP_TO
 #define ICON_CHANLIST_COPY GTK_STOCK_COPY
 #define ICON_CHANLIST_FIND GTK_STOCK_FIND
@@ -736,8 +735,7 @@ chanlist_button_cb (GtkTreeView *tree, GdkEventButton *event, server *serv)
 										  GDK_GRAVITY_NORTH_WEST,
 										  NULL);
 	}
-#endif
-#if !HAVE_GTK3
+#else
 	gtk_menu_popup (GTK_MENU (menu), NULL, NULL, NULL, NULL, 0, event ? event->time : 0);
 #endif
 

src/fe-gtk/menu.c

@@ -596,8 +596,7 @@ menu_popup (GtkWidget *menu, GdkEventButton *event, gpointer objtounref)
 	{
 		gtk_menu_popup_at_pointer (GTK_MENU (menu), NULL);
 	}
-#endif
-#if !HAVE_GTK3
+#else
 	gtk_menu_popup (GTK_MENU (menu), NULL, NULL, NULL, NULL,
 						 0, event ? event->time : 0);
 #endif
@@ -1842,8 +1841,7 @@ menu_about (GtkWidget *wid, gpointer sess)
 #define ICON_FIND "edit-find"
 #define ICON_HELP "help-browser"
 #define ICON_ABOUT "help-about"
-#endif
-#if !HAVE_GTK3
+#else
 #define ICON_NEW GTK_STOCK_NEW
 #define ICON_LOAD_PLUGIN GTK_STOCK_REVERT_TO_SAVED
 #define ICON_DETACH GTK_STOCK_REDO

src/fe-gtk/plugingui.c

@@ -52,8 +52,7 @@ static GtkWidget *plugin_window = NULL;
 #define ICON_PLUGIN_LOAD "document-open"
 #define ICON_PLUGIN_UNLOAD "edit-delete"
 #define ICON_PLUGIN_RELOAD "view-refresh"
-#endif
-#if !HAVE_GTK3
+#else
 #define ICON_PLUGIN_LOAD GTK_STOCK_REVERT_TO_SAVED
 #define ICON_PLUGIN_UNLOAD GTK_STOCK_DELETE
 #define ICON_PLUGIN_RELOAD GTK_STOCK_REFRESH