diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index c464b17da4..a90592628a 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -1277,6 +1277,42 @@ AP_Param *AP_Param::next_scalar(ParamToken *token, enum ap_var_type *ptype)
     AP_Param *ap;
     enum ap_var_type type;
     while ((ap = next(token, &type)) != NULL && type > AP_PARAM_FLOAT) ;
+
+    if (ap != NULL && type == AP_PARAM_INT8) {
+        /* 
+           check if this is an enable variable. To do that we need to
+           find the info structures for the variable
+         */
+        uint32_t group_element;
+        const struct GroupInfo *ginfo;
+        const struct GroupInfo *ginfo0;
+        uint8_t idx;
+        const struct AP_Param::Info *info = ap->find_var_info_token(*token, &group_element, ginfo, ginfo0, &idx);
+        if (info && ginfo &&
+            (ginfo->flags & AP_PARAM_FLAG_ENABLE) &&
+            ((AP_Int8 *)ap)->get() == 0) {
+            /*
+              this is a disabled parameter tree, include this
+              parameter but not others below it. We need to keep
+              looking until we go past the parameters in this object
+            */
+            ParamToken token2 = *token;
+            enum ap_var_type type2;
+            AP_Param *ap2;
+            while ((ap2 = next(&token2, &type2)) != NULL) {
+                if (token2.key != token->key) {
+                    break;
+                }
+                if (ginfo0 != NULL && (token->group_element & 0x3F) != (token2.group_element & 0x3F)) {
+                    break;
+                }
+                // update the returned token so the next() call goes from this point
+                *token = token2;
+            }
+            
+        }
+    }
+
     if (ap != NULL && ptype != NULL) {
         *ptype = type;
     }
diff --git a/libraries/AP_Param/AP_Param.h b/libraries/AP_Param/AP_Param.h
index 3e5e99e12f..818ce64f8e 100644
--- a/libraries/AP_Param/AP_Param.h
+++ b/libraries/AP_Param/AP_Param.h
@@ -35,9 +35,17 @@
 /*
   flags for variables in var_info and group tables
  */
+
+// a nested offset is for subgroups that are not subclasses
 #define AP_PARAM_FLAG_NESTED_OFFSET 1
+
+// a pointer variable is for dynamically allocated objects
 #define AP_PARAM_FLAG_POINTER       2
 
+// an enable variable allows a whole subtree of variables to be made
+// invisible
+#define AP_PARAM_FLAG_ENABLE        4
+
 // a variant of offsetof() to work around C++ restrictions.
 // this can only be used when the offset of a variable in a object
 // is constant and known at compile time
@@ -47,7 +55,10 @@
 #define AP_CLASSTYPE(class, element) ((uint8_t)(((const class *) 1)->element.vtype))
 
 // declare a group var_info line
-#define AP_GROUPINFO(name, idx, class, element, def) { AP_CLASSTYPE(class, element), idx, name, AP_VAROFFSET(class, element), {def_value : def} }
+#define AP_GROUPINFO_FLAGS(name, idx, class, element, def, flags) { AP_CLASSTYPE(class, element), idx, name, AP_VAROFFSET(class, element), {def_value : def}, flags }
+
+// declare a group var_info line
+#define AP_GROUPINFO(name, idx, class, element, def) AP_GROUPINFO_FLAGS(name, idx, class, element, def, 0)
 
 // declare a nested group entry in a group var_info
 #define AP_NESTEDGROUPINFO(class, idx) { AP_PARAM_GROUP, idx, "", 0, { group_info : class::var_info }, 0 }