UI: Fix mem leak in VolControl

UI/slider-absoluteset-style.hpp

@@ -6,7 +6,7 @@ class SliderAbsoluteSetStyle : public QProxyStyle
 {
 public:
 	SliderAbsoluteSetStyle(const QString& baseStyle);
-	SliderAbsoluteSetStyle(QStyle* baseStyle);
+	SliderAbsoluteSetStyle(QStyle* baseStyle = Q_NULLPTR);
 	int styleHint(QStyle::StyleHint hint, const QStyleOption* option,
 		const QWidget* widget, QStyleHintReturn* returnData) const;
 };

UI/volume-control.cpp

@@ -9,6 +9,7 @@
 #include <QSlider>
 #include <QLabel>
 #include <QPainter>
+#include <QStyleFactory>
 
 using namespace std;
 
@@ -246,7 +247,17 @@ VolControl::VolControl(OBSSource source_, bool showConfig, bool vertical)
 	obs_fader_attach_source(obs_fader, source);
 	obs_volmeter_attach_source(obs_volmeter, source);
 
-	slider->setStyle(new SliderAbsoluteSetStyle(slider->style()));
+	QString styleName = slider->style()->objectName();
+	QStyle *style;
+	style = QStyleFactory::create(styleName);
+	if (!style) {
+		style = new SliderAbsoluteSetStyle();
+	} else {
+		style = new SliderAbsoluteSetStyle(style);
+	}
+
+	style->setParent(slider);
+	slider->setStyle(style);
 
 	/* Call volume changed once to init the slider position and label */
 	VolumeChanged();