BUG: Odd registration key in itk : the tag is the position is the observer...

BUG: Odd registration key in itk : the tag is the position is the observer list, so it becomes invalid if another observer was removed before. Trying to overcome the problem by removing observers in the reverse order wrt the add order

Code/Common/otbFilterWatcherBase.cxx

@@ -69,18 +69,7 @@ FilterWatcherBase
   // Remove any observers we have on the old process object
   if (m_Process)
   {
-    if (m_StartFilterCommand)
-    {
-      m_Process->RemoveObserver(m_StartTag);
-    }
-    if (m_EndFilterCommand)
-    {
-      m_Process->RemoveObserver(m_EndTag);
-    }
-    if (m_ProgressFilterCommand)
-    {
-      m_Process->RemoveObserver(m_ProgressTag);
-    }
+  m_Process->RemoveAllObservers(); 
   }
 
   // Initialize state
@@ -122,18 +111,7 @@ FilterWatcherBase
   // Remove any observers we have on the old process object
   if (m_Process)
   {
-    if (m_StartFilterCommand)
-    {
-      m_Process->RemoveObserver(m_StartTag);
-    }
-    if (m_EndFilterCommand)
-    {
-      m_Process->RemoveObserver(m_EndTag);
-    }
-    if (m_ProgressFilterCommand)
-    {
-      m_Process->RemoveObserver(m_ProgressTag);
-    }
+  m_Process->RemoveAllObservers(); 
   }
 
   // Initialize state
@@ -173,19 +151,8 @@ FilterWatcherBase
 {
   // Remove any observers we have on the old process object
   if (m_Process)
-  {
-    if (m_StartFilterCommand)
-    {
-      m_Process->RemoveObserver(m_StartTag);
-    }
-    if (m_EndFilterCommand)
-    {
-      m_Process->RemoveObserver(m_EndTag);
-    }
-    if (m_ProgressFilterCommand)
-    {
-      m_Process->RemoveObserver(m_ProgressTag);
-    }
+  {   
+  m_Process->RemoveAllObservers();
   }
 }