diff -r 36f1581b43e2 -r 40dbf1a7526a ui/common/context.c
--- a/ui/common/context.c	Sun Jan 24 12:39:05 2016 +0100
+++ b/ui/common/context.c	Sun Jan 24 18:47:39 2016 +0100
@@ -38,19 +38,14 @@
 
 UiContext* uic_context(UiObject *toplevel, UcxMempool *mp) {
     UiContext *ctx = ucx_mempool_malloc(mp, sizeof(UiContext));
-    ctx->parent = NULL;
+    memset(ctx, 0, sizeof(UiContext));
     ctx->mempool = mp;
-    ctx->document = NULL;
     ctx->obj = toplevel;
     ctx->vars = ucx_map_new_a(mp->allocator, 16);
-    ctx->groups = NULL;
-    ctx->group_widgets = NULL;
     
     ctx->set_document = uic_context_set_document;
     ctx->detach_document = uic_context_detach_document;
     
-    ctx->title = NULL;
-    
 #ifdef UI_GTK
     if(toplevel->widget) {
         ctx->accel_group = gtk_accel_group_new();
@@ -334,6 +329,11 @@
 
 // public API
 
+void ui_context_closefunc(UiContext *ctx, ui_callback fnc, void *udata) {
+    ctx->close_callback = fnc;
+    ctx->close_data = udata;
+}
+
 int ui_getint(UiObject *obj, char *name) {
     UiVar *var = uic_get_var(obj->ctx, name);
     if(var) {