check SelectionForbidsCellFill() on EnterBlock()

... to prevent Alt+Enter filling a huge selection.

Change-Id: I8ce905c6e5ad0cb4dadf309f7b995142414e7193

sc/source/ui/view/viewfun2.cxx

@@ -750,6 +750,12 @@ void ScViewFunc::EnterBlock( const OUString& rString, const EditTextObject* pDat
         }
     }
 
+    if (GetViewData().SelectionForbidsCellFill())
+    {
+        PaintArea(nCol, nRow, nCol, nRow);        // possibly the edit-engine is still painted there
+        return;
+    }
+
     ScDocument* pDoc = GetViewData().GetDocument();
     OUString aNewStr = rString;
     if ( pData )