seems to work

Author: Davide Faconti

bt_editor/custom_node_dialog.cpp

@@ -69,6 +69,7 @@ CustomNodeDialog::CustomNodeDialog(const NodeModels &models,
             else if( model.type == NodeType::SUBTREE )
             {
                 ui->comboBox->setCurrentIndex(2);
+                ui->comboBox->setEnabled(false);
             }
         }
     }

bt_editor/resources/stylesheet.qss

@@ -29,3 +29,9 @@ QComboBox {
     padding-left: 4px;
     padding-right: 4px;
 }
+
+QComboBox:disabled {
+    color: blue;
+    background-color: grey;
+    selection-background-color: grey;
+}

test_data/subtree_test_fail.xml

@@ -10,17 +10,7 @@
             <!--  compact syntax  -->
             <SubTree ID="ThisOne"   target="{goal}" result="{out}" />
             <SubTree ID="TheOther"  target="{goal}" result="{out}" />
-            
-            <!--  veebose syntax  -->
-            <SubTree ID="ThisOne">
-                <remap internal="target" external="{goal}"/>
-                <remap internal="result" external="{out}"/>
-            </SubTree>    
-            <SubTree ID="TheOther">
-                <remap internal="target" external="{goal}"/>
-                <remap internal="result" external="{out}"/>
-            </SubTree> 
-            
+       
         </Sequence>
     </BehaviorTree>
     <!--  //////////  -->