[calamares] No need for progresstreeview to be singleton

src/calamares/progresstree/ProgressTreeView.cpp

@@ -23,19 +23,9 @@
 #include "Branding.h"
 #include "ViewManager.h"
 
-ProgressTreeView* ProgressTreeView::s_instance = nullptr;
-
-ProgressTreeView*
-ProgressTreeView::instance()
-{
-    return s_instance;
-}
-
 ProgressTreeView::ProgressTreeView( QWidget* parent )
     : QTreeView( parent )
 {
-    s_instance = this;  //FIXME: should assert when s_instance gets written and it wasn't nullptr
-
     this->setObjectName( "sidebarMenuApp" );
     setFrameShape( QFrame::NoFrame );
     setContentsMargins( 0, 0, 0, 0 );

src/calamares/progresstree/ProgressTreeView.h

@@ -27,14 +27,11 @@ class ProgressTreeDelegate;
 /**
  * @brief The ProgressTreeView class is a modified QTreeView which displays the
  * available view steps and the user's progress through them.
- * @note singleton, only access through ProgressTreeView::instance().
  */
 class ProgressTreeView : public QTreeView
 {
     Q_OBJECT
 public:
-    static ProgressTreeView* instance();
-
     explicit ProgressTreeView( QWidget* parent = nullptr );
     virtual ~ProgressTreeView() override;
 
@@ -44,7 +41,6 @@ public:
     void setModel( QAbstractItemModel* model ) override;
 
 private:
-    static ProgressTreeView* s_instance;
     ProgressTreeDelegate* m_delegate;
 };