diff -r cc2170ea05ad -r 46448d38885c ui/gtk/toolkit.h
--- a/ui/gtk/toolkit.h	Fri Nov 10 18:04:40 2017 +0100
+++ b/ui/gtk/toolkit.h	Sat Nov 11 08:34:06 2017 +0100
@@ -44,6 +44,12 @@
     int         value;
 } UiEventData;
 
+typedef struct UiVarEventData {
+    UiObject   *obj;
+    UiVar      *var;
+} UiVarEventData;
+
+
 typedef struct UiJob {
     UiObject      *obj;
     ui_threadfunc job_func;
@@ -61,7 +67,7 @@
 #endif
 
 void ui_destroy_userdata(GtkWidget *object, void *userdata);
-
+void ui_destroy_vardata(GtkWidget *object, UiVarEventData *data);
 void ui_destroy_boundvar(UiContext *ctx, UiVar *var);
 
 void ui_set_active_window(UiObject *obj);