fs34b: #i117039# restore old behavior of SfxUndoManager::EnableUndo: don't count…

fs34b: #i117039# restore old behavior of SfxUndoManager::EnableUndo: don't count the calls, but maintain a simple flag.
Consequently, let sw's UndoManager simply delegate now, and change the UndoManagerHelper to maintain a lock counter itself.

svl/inc/svl/undo.hxx

@@ -315,9 +315,14 @@ namespace svl
         /** clears the redo stack and removes the top undo action */
         virtual void            RemoveLastUndoAction() = 0;
 
-        // enables (true) or disables (false) recording of undo actions
-        // If undo actions are added while undo is disabled, they are deleted.
-        // Disabling undo does not clear the current undo buffer!
+        /** enables (true) or disables (false) recording of undo actions
+
+            If undo actions are added while undo is disabled, they are deleted.
+            Disabling undo does not clear the current undo buffer!
+
+            Multiple calls to <code>EnableUndo</code> are not cumulative. That is, calling <code>EnableUndo( false )</code>
+            twice, and then calling <code>EnableUndo( true )</code> means that Undo is enable afterwards.
+        */
         virtual void            EnableUndo( bool bEnable ) = 0;
 
         // returns true if undo is currently enabled

svl/source/undo/undo.cxx

@@ -185,9 +185,9 @@ struct SVL_DLLPRIVATE SfxUndoManager_Data
     SfxUndoArray*   pActUndoArray;
     SfxUndoArray*   pFatherUndoArray;
 
-    sal_Int32       mnLockCount;
     sal_Int32       mnMarks;
     sal_Int32       mnEmptyMark;
+    bool            mbUndoEnabled;
     bool            mbDoing;
     bool            mbClearUntilTopLevel;
 
@@ -197,9 +197,9 @@ struct SVL_DLLPRIVATE SfxUndoManager_Data
         :pUndoArray( new SfxUndoArray( i_nMaxUndoActionCount ) )
         ,pActUndoArray( NULL )
         ,pFatherUndoArray( NULL )
-        ,mnLockCount( 0 )
         ,mnMarks( 0 )
         ,mnEmptyMark(MARK_INVALID)
+        ,mbUndoEnabled( true )
         ,mbDoing( false )
         ,mbClearUntilTopLevel( false )
     {
@@ -420,14 +420,9 @@ void SfxUndoManager::EnableUndo( bool i_enable )
 
 void SfxUndoManager::ImplEnableUndo_Lock( bool const i_enable )
 {
-    if ( !i_enable )
-        ++m_pData->mnLockCount;
-    else
-    {
-        OSL_PRECOND( m_pData->mnLockCount > 0, "SfxUndoManager::ImplEnableUndo_NoNotify: not disabled, so why enabling?" );
-        if ( m_pData->mnLockCount > 0 )
-            --m_pData->mnLockCount;
-    }
+    if ( m_pData->mbUndoEnabled == i_enable )
+        return;
+    m_pData->mbUndoEnabled = i_enable;
 }
 
 //------------------------------------------------------------------------
@@ -442,7 +437,7 @@ bool SfxUndoManager::IsUndoEnabled() const
 
 bool SfxUndoManager::ImplIsUndoEnabled_Lock() const
 {
-    return m_pData->mnLockCount == 0;
+    return m_pData->mbUndoEnabled;
 }
 
 //------------------------------------------------------------------------