corr groupbox heirarchy, get rid of runtime warning

GUI/View/Instrument/DetectorEditor.cpp

@@ -38,7 +38,7 @@ DetectorEditor::DetectorEditor(QWidget* parent, GISASInstrumentItem* instrItem)
     DetectorItem* detectorItem = instrItem->detectorItem();
     ASSERT(detectorItem);
 
-    auto* grid = new QGridLayout(this);
+    auto* grid = new QGridLayout;
     grid->setColumnStretch(0, 1);
     grid->setColumnStretch(1, 1);
     grid->setColumnStretch(2, 1);