make square version of thumb for icon view

ui/otreeview.cpp

@@ -0,0 +1,9 @@
+#include "otreeview.h"
+
+OTreeView::OTreeView(QWidget *parent) : QTreeView(parent) {
+    setSortingEnabled(true);
+    sortByColumn(0, Qt::AscendingOrder);
+    setContextMenuPolicy(Qt::CustomContextMenu);
+    connect(this, SIGNAL(customContextMenuRequested(const QPoint&)), this, SLOT(show_context_menu()));
+    connect(this, SIGNAL(clicked(const QModelIndex&)), this, SLOT(item_click(const QModelIndex&)));
+}

ui/otreeview.h

@@ -0,0 +1,16 @@
+#ifndef OTREEVIEW_H
+#define OTREEVIEW_H
+
+#include <QTreeView>
+
+#include "ui/sourcetable.h"
+
+class OTreeView : public QTreeView {
+    Q_OBJECT
+public:
+    OTreeView(QWidget* parent = 0);
+private:
+
+};
+
+#endif // OTREEVIEW_H