UI: Add ability to reset sliders when double clicked

UI/balance-slider.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QSlider>
+#include <QMouseEvent>
+
+class BalanceSlider : public QSlider {
+	Q_OBJECT
+
+public:
+	inline BalanceSlider(QWidget *parent = 0) : QSlider(parent) {}
+
+signals:
+	void doubleClicked();
+
+protected:
+	void mouseDoubleClickEvent(QMouseEvent *event)
+	{
+		emit doubleClicked();
+		event->accept();
+	}
+};