patch 7.4.1811
Problem:    Netbeans channel gets garbage collected.
Solution:   Set reference in nb_channel.
diff --git a/src/netbeans.c b/src/netbeans.c
index b0e7d9e..a80067f 100644
--- a/src/netbeans.c
+++ b/src/netbeans.c
@@ -2585,6 +2585,23 @@
     }
 }
 
+#if defined(FEAT_EVAL) || defined(PROTO)
+    int
+set_ref_in_nb_channel(int copyID)
+{
+    int abort = FALSE;
+    typval_T tv;
+
+    if (nb_channel != NULL)
+    {
+	tv.v_type = VAR_CHANNEL;
+	tv.vval.v_channel = nb_channel;
+	abort = set_ref_in_item(&tv, copyID, NULL, NULL);
+    }
+    return abort;
+}
+#endif
+
 #if defined(FEAT_GUI_X11) || defined(FEAT_GUI_W32) || defined(PROTO)
 /*
  * Tell netbeans that the window was moved or resized.