VerticalTabs: Switch tabs with mouse wheel

But only when there is no scrollbar in normal tabs view.

src/plugins/VerticalTabs/verticaltabswidget.cpp

@@ -27,8 +27,10 @@
 #include "tabbedwebview.h"
 #include "browserwindow.h"
 
-#include <QVBoxLayout>
 #include <QListView>
+#include <QScrollBar>
+#include <QVBoxLayout>
+#include <QWheelEvent>
 
 VerticalTabsWidget::VerticalTabsWidget(BrowserWindow *window)
     : QWidget()
@@ -146,3 +148,29 @@ WebTab *VerticalTabsWidget::previousTab() const
     }
     return previous.data(TabModel::WebTabRole).value<WebTab*>();
 }
+
+void VerticalTabsWidget::wheelEvent(QWheelEvent *event)
+{
+    if (m_normalView->verticalScrollBar()->isVisible()) {
+        return;
+    }
+
+    m_wheelHelper.processEvent(event);
+    while (WheelHelper::Direction direction = m_wheelHelper.takeDirection()) {
+        switch (direction) {
+        case WheelHelper::WheelUp:
+        case WheelHelper::WheelLeft:
+            switchToPreviousTab();
+            break;
+
+        case WheelHelper::WheelDown:
+        case WheelHelper::WheelRight:
+            switchToNextTab();
+            break;
+
+        default:
+            break;
+        }
+    }
+    event->accept();
+}

src/plugins/VerticalTabs/verticaltabswidget.h

@@ -19,6 +19,8 @@
 
 #include <QWidget>
 
+#include "wheelhelper.h"
+
 #include "verticaltabsplugin.h"
 
 class WebTab;
@@ -40,6 +42,8 @@ public:
     void switchToPreviousTab();
 
 private:
+    void wheelEvent(QWheelEvent *event) override;
+
     WebTab *nextTab() const;
     WebTab *previousTab() const;
 
@@ -47,4 +51,5 @@ private:
     TabListView *m_pinnedView;
     TabTreeView *m_normalView;
     TabTreeModel *m_treeModel = nullptr;
+    WheelHelper m_wheelHelper;
 };