construct DataView from low to high level

GUI/View/Views/DataView.cpp

@@ -20,17 +20,15 @@
 
 DataView::DataView()
 {
-    auto* layout = new QVBoxLayout(this);
-
-    auto* splitter = new QSplitter;
-    layout->addWidget(splitter);
-
     auto* stacked_frames = new StackedDataFrames;
     auto* selector = new DatafilesSelector;
 
+    auto* splitter = new QSplitter;
     splitter->addWidget(selector);
     splitter->addWidget(stacked_frames);
-
     splitter->setCollapsible(0, false);
     splitter->setCollapsible(1, false);
+
+    auto* layout = new QVBoxLayout(this);
+    layout->addWidget(splitter);
 }