QPushButton in a sub-QMenu, change background on hover - c++

Question

EDIT:
NOTE this only occurs when the button is in a SUBMENU. (Menu in a menu.) This code works fine only on the parent menu!
Running Qt 5.0.2, on Windows 7. I have a QMenu with a QWidgetAction in it. Inside the QWidgetAction is a QPushButton. I would like to change the background color of the button when the mouse hovers over it.
Here is my code:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QMenu>
#include <QWidgetAction>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
QMenu menu;
QMenu *subMenu = new QMenu("SubMenu text");
QWidgetAction *widgetAction = new QWidgetAction(subMenu);
QPushButton *btn = new QPushButton("test");
btn->setStyleSheet("QPushButton:hover{background-color: #ff0000;}");
widgetAction->setDefaultWidget(btn);
subMenu->addAction(widgetAction);
menu.addMenu(subMenu);
menu.exec();
}
.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_pushButton_clicked();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
However when the cursor hovers over the QPushButton the background color doesn't change. Doesn't matter if I run it in fusion style or not.
What is going on here? Thanks for your time.

Answer 1

This sound like mouseTracking is not enabled on the widget (and/or probably on the parent widget(s)). You can enable it by calling
QWidget::setMouseTracking(bool enable);

Answer 2

Background may not be customized, if you don't change a border style of a button.
How to solve: use some non-default style, for example:
const auto fusion = QStyleFactory::create( "Fusion" );
QApplication::setStyle( fusion );
QPushButton is not designed for perfect handling hover events. For example, hover event will not change a font via stylesheet.
How to solve: use QToolButton instead.
P.S. Don't know, why it's not worked for you. Everything is OK for me...
UPDATE
Just copy-paste it and run:
#include <QApplication>
#include <QWidgetAction>
#include <QMenu>
#include <QPushButton>
#include <QToolButton>
#include <QStyleFactory>
void showMenu()
{
const auto parent = qApp->activeWindow();
auto menu = new QMenu( parent );
auto root = new QMenu( "Root", menu );
menu->addMenu( root );
auto wa = new QWidgetAction( parent );
auto tb = new QToolButton;
tb->setText( "ToolBtn" );
wa->setDefaultWidget( tb );
root->addAction( wa );
menu->exec( QCursor::pos() );
menu->deleteLater();
}
int main(int argc, char *argv[])
{
QApplication a( argc, argv );
const auto fusion = QStyleFactory::create( "Fusion" );
const auto qss =
"QToolButton:!hover{background-color: #00ff00;}"
"QToolButton:hover{background-color: #ff0000;}"
;
QApplication::setStyle( fusion );
qApp->setStyleSheet( qss );
QWidget w;
w.resize( 800, 600 );
auto btn = new QPushButton{ "Test", &w };
QObject::connect( btn, &QPushButton::clicked, &showMenu );
w.show();
return a.exec();
}