Add scroll-down button

include/ui/FloatingButton.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "RaisedButton.h"
+
+constexpr int DIAMETER  = 40;
+constexpr int ICON_SIZE = 18;
+
+constexpr int OFFSET_X = 30;
+constexpr int OFFSET_Y = 20;
+
+class FloatingButton : public RaisedButton
+{
+        Q_OBJECT
+
+public:
+        FloatingButton(const QIcon &icon, QWidget *parent = nullptr);
+
+        QSize sizeHint() const override { return QSize(DIAMETER, DIAMETER); };
+        QRect buttonGeometry() const;
+
+protected:
+        bool event(QEvent *event) override;
+        bool eventFilter(QObject *obj, QEvent *event) override;
+
+        void paintEvent(QPaintEvent *event) override;
+};