Remove the algorithm from the manager on a reject call...

but only if we were supposed to execute on accept. If we are executing
on accept then we are assuming that the AlgorithmManager owns the
algorithm pointer as it must survive after the dialog is destroyed.
Refs #9756

Code/Mantid/MantidQt/API/inc/MantidQtAPI/AlgorithmDialog.h

@@ -216,6 +216,8 @@ protected slots:
 
   /// Executes the algorithm in a separate thread
   virtual void executeAlgorithmAsync();
+  /// Removes the algorithm from the manager.
+  virtual void removeAlgorithmFromManager();
 
 protected:
 

Code/Mantid/MantidQt/API/src/AlgorithmDialog.cpp

@@ -2,8 +2,7 @@
 // Includes
 //----------------------------------
 #include "MantidAPI/FileProperty.h"
-#include "MantidAPI/FrameworkManager.h"
-#include "MantidAPI/IAlgorithm.h"
+#include "MantidAPI/AlgorithmManager.h"
 #include "MantidAPI/IWorkspaceProperty.h"
 #include "MantidAPI/MultipleFileProperty.h"
 #include "MantidKernel/DateAndTime.h"
@@ -734,8 +733,8 @@ void AlgorithmDialog::accept()
   }
 }
 
-
 //-------------------------------------------------------------------------------------------------
+
 /**
  * A slot to handle the help button click
  */
@@ -766,6 +765,15 @@ void AlgorithmDialog::executeAlgorithmAsync()
   }
 }
 
+//-------------------------------------------------------------------------------------------------
+/*
+ */
+void AlgorithmDialog::removeAlgorithmFromManager()
+{
+  using namespace Mantid::API;
+  AlgorithmManager::Instance().removeById(m_algorithm->getAlgorithmID());
+}
+
 //------------------------------------------------------
 // Private member functions
 //------------------------------------------------------
@@ -856,8 +864,16 @@ void AlgorithmDialog::isForScript(bool forScript)
  */
 void AlgorithmDialog::executeOnAccept(bool on)
 {
-  if(on) connect(this, SIGNAL(accepted()), this, SLOT(executeAlgorithmAsync()));
-  else disconnect(this, SIGNAL(accepted()), this, SLOT(executeAlgorithmAsync()));
+  if(on)
+  {
+    connect(this, SIGNAL(accepted()), this, SLOT(executeAlgorithmAsync()));
+    connect(this, SIGNAL(rejected()), this, SLOT(removeAlgorithmFromManager()));
+  }
+  else
+  {
+    disconnect(this, SIGNAL(accepted()), this, SLOT(executeAlgorithmAsync()));
+    disconnect(this, SIGNAL(rejected()), this, SLOT(removeAlgorithmFromManager()));
+  }
 }
 
 //-------------------------------------------------------------------------------------------------