QWidget is transparent even if I set the background color

Aaron Kim

I want to make a menu (yellow square) which is shown up if I press the button. Because there is a layout, I have to set its parent to MainWindow and set its coordinate.

I made a snippet to test it.

class ConstMenu : public QWidget{
    Q_OBJECT

private:
    MainWindow* mainWindow;
    Template::Calculator* calculator;
    void mousePressEvent(QMouseEvent*);

public:
    ConstMenu(MainWindow*, Template::Calculator*);
    virtual ~ConstMenu() = default;
    void showMenu();
};
ConstMenu::ConstMenu(MainWindow* window, Template::Calculator* cal) : QWidget(window),
    mainWindow(window), calculator(cal) {
    this->showMenu();
}


void ConstMenu::showMenu(){
    this->setStyleSheet("background-color: red;");
    this->move(0, 0);
    this->resize(300, 300);
    this->show();
}

void ConstMenu::mousePressEvent(QMouseEvent*){
    std::cout << "Test\n";
}

However, nothing is shown.

The strange thing is, there is definitely the ConstMenu widget because I checked it with mousePressEvent.
It is there, but transparent.

(You can see buttons at the bottom are highlighted when mouse hovers them, unlike other buttons at the top. This is because the ConstMenu widget covers them)

I have never experienced such odd behavior. Any guess?

SGaist

Hi,

That is strange indeed. Just one question though, why not use QToolButton which already provides handling for an associated menu ?

Aaron Kim

@SGaist ConstMenu class is not a button, but a panel on which buttons are
There will be buttons on the yellow square

SGaist

Try setting the autoFillBackground property to true.