diff --git a/Fltk/onelabWindow.cpp b/Fltk/onelabWindow.cpp
index ea5e0cb48e25cd719c1a17b70d6115db4b39923e..28e8830246a51038da0d8b2dc977d97c84793645 100644
--- a/Fltk/onelabWindow.cpp
+++ b/Fltk/onelabWindow.cpp
@@ -958,6 +958,8 @@ void onelabWindow::rebuildTree()
     free(_treeStrings[i]);
   _treeStrings.clear();
 
+  FlGui::check(); // necessary e.g. on windows to avoid "ghosting"
+
   std::vector<onelab::number> numbers;
   onelab::server::instance()->get(numbers);
   for(unsigned int i = 0; i < numbers.size(); i++){