It's a tricky one. Since you added the Q_OBJECT macro to your subclass, you need to re-implement the paintEvent method to render your widget with style sheet support.
#ifndef MATRIZ_H
#define MATRIZ_H
#include <QWidget>
class QHBoxLayout;
class Matriz : public QWidget{
Q_OBJECT
private:
QHBoxLayout* lay {nullptr};
public:
explicit Matriz(QWidget* parent = nullptr);
virtual ~Matriz() = default;
void paintEvent(QPaintEvent *paintEvent) override;
};
#endif
#include "matriz.h"
#include <QHBoxLayout>
#include <QPainter>
#include <QStyle>
#include <QStyleOption>
Matriz::Matriz(QWidget* parent) : QWidget(parent){
lay = new QHBoxLayout;
setLayout(lay); //apply layout to this widget
}
void Matriz::paintEvent(QPaintEvent *paintEvent)
{
Q_UNUSED(paintEvent);
QStyleOption option;
option.initFrom(this);
QPainter painter(this);
style()->drawPrimitive(QStyle::PE_Widget, &option, &painter, this);
};
On a side note, next time you post code, ensure that it properly builds.
