Merge pull request #208 from atsju/JST/fix193

fix code that mixes wavefront index and name

Author: gr5

surfacemanager.cpp

@@ -1788,8 +1788,9 @@ void SurfaceManager::subtractWavefronts(){
     QList<QString> list;
     QList<int> doThese =  m_surfaceTools->SelectedWaveFronts();
     for (int i = 0; i < m_wavefronts.size(); ++i){
-        if (!m_wavefronts[i]->name.contains(doThese[0]))
+        if (!doThese.contains(i)) {
              list.append(m_wavefronts[i]->name);
+        }
     }
     subtractWavefronatsDlg dlg(list);
     QScreen *screen = QGuiApplication::primaryScreen();