--- fio-3.20/gfio.c	2020-05-23 18:14:14.000000000 +0100
+++ /tmp/gfio.c	2020-07-04 16:48:41.984917631 +0100
@@ -51,6 +51,8 @@
 static void start_job_clicked(GtkWidget *widget, gpointer data);
 static void send_clicked(GtkWidget *widget, gpointer data);
 
+struct gui main_ui;
+
 static struct button_spec {
 	const char *buttontext;
 	clickfunction f;
--- fio-3.20/gfio.h	2020-05-23 18:14:14.000000000 +0100
+++ /tmp/gfio.h	2020-07-04 16:48:41.984917631 +0100
@@ -53,7 +53,7 @@
 /*
  * Main window widgets and data
  */
-struct gui {
+extern struct gui {
 	GtkUIManager *uimanager;
 	GtkRecentManager *recentmanager;
 	GtkActionGroup *actiongroup;