PD: Delete support if invalid after changing mapping mode

src/Mod/Part/App/AttachExtension.cpp

@@ -30,6 +30,8 @@
 #include <Base/Console.h>
 #include <App/Application.h>
 
+#include <App/DocumentObject.h>
+
 #include <App/FeaturePythonPyImp.h>
 #include "AttachExtensionPy.h"
 
@@ -135,8 +137,36 @@ short int AttachExtension::extensionMustExecute(void) {
 App::DocumentObjectExecReturn *AttachExtension::extensionExecute()
 {
     if(this->isTouched_Mapping()) {
+
+        if (!_attacher)
+            throw Base::Exception("AttachExtension: can't positionBySupport, because no AttachEngine is set.");
+        updateAttacherVals();
+
+        SuggestResult sr;
+
+        _attacher->suggestMapModes(sr);
+
+        bool acceptableattachment = false;
+
+        for(std::vector<eMapMode>::const_iterator it = sr.allApplicableModes.begin() ; it != sr.allApplicableModes.end(); it++)
+        {
+            if ( (*it) == eMapMode(this->MapMode.getValue()))
+                acceptableattachment = true;
+        }
+
         try{
-            positionBySupport();
+            if(acceptableattachment) {
+                positionBySupport();
+            }
+            else {
+                std::vector<App::DocumentObject*> Objects     = this->Support.getValues();
+                std::vector<std::string>     SubElements     = this->Support.getSubValues();
+
+                Objects.clear();
+                SubElements.clear();
+
+                this->Support.setValues(Objects,SubElements);
+            }
         } catch (Base::Exception &e) {
             return new App::DocumentObjectExecReturn(e.what());
         } catch (Standard_Failure &e){