[AdBlockTreeWidget] Greatly speedup loading rules from subscriptions

Don't use per-pixel scrolling. For some reason, it massively slows
rendering of TreeWidget

See #1169

src/lib/adblock/adblocktreewidget.cpp

@@ -235,6 +235,7 @@ void AdBlockTreeWidget::refresh()
     m_topItem = new QTreeWidgetItem(this);
     m_topItem->setText(0, m_subscription->title());
     m_topItem->setFont(0, boldFont);
+    m_topItem->setExpanded(true);
     addTopLevelItem(m_topItem);
 
     const QVector<AdBlockRule*> &allRules = m_subscription->allRules();
@@ -253,7 +254,6 @@ void AdBlockTreeWidget::refresh()
         ++index;
     }
 
-    expandAll();
     showRule(0);
     m_itemChangingBlock = false;
 }

src/lib/adblock/adblocktreewidget.h

@@ -18,8 +18,6 @@
 #ifndef ADBLOCKTREEWIDGET_H
 #define ADBLOCKTREEWIDGET_H
 
-#include <QTreeWidget>
-
 #include "qz_namespace.h"
 #include "treewidget.h"
 

src/lib/tools/treewidget.cpp

@@ -32,8 +32,6 @@ TreeWidget::TreeWidget(QWidget* parent)
     , m_refreshAllItemsNeeded(true)
     , m_showMode(ItemsCollapsed)
 {
-    setVerticalScrollMode(QAbstractItemView::ScrollPerPixel);
-
     connect(this, SIGNAL(itemChanged(QTreeWidgetItem*,int)), this, SLOT(sheduleRefresh()));
 }
 
@@ -325,6 +323,7 @@ QList<QTreeWidgetItem*> TreeWidget::allItems()
         iterateAllItems(0);
         m_refreshAllItemsNeeded = false;
     }
+
     return m_allTreeItems;
 }
 

src/lib/tools/treewidget.h

@@ -31,6 +31,7 @@ public:
     ItemShowMode defaultItemShowMode() { return m_showMode; }
     void setDefaultItemShowMode(ItemShowMode mode) { m_showMode = mode; }
     QList<QTreeWidgetItem*> allItems();
+
     bool appendToParentItem(const QString &parentText, QTreeWidgetItem* item);
     bool appendToParentItem(QTreeWidgetItem* parent, QTreeWidgetItem* item);
     bool prependToParentItem(const QString &parentText, QTreeWidgetItem* item);