How to use TAB Key to focus one of two qpushbutton - qt

Question

In a widget I put two QPushButton (let's say "OK" at left and "EXIT" at right).
They regularly work when I press them using the mouse.
Suppose I want to switch from one to the other using TAB key: is it possible?
And how can do this?

Answer 1

On some platforms, keyboard focus navigation among buttons is a default behavior, but on some it isn't.
If you wish keyboard navigation on all platforms, the buttons should have a Qt::StrongFocus policy set on them. Note that the shortcut used to trigger the buttons is also platform-specific. E.g. on OS X you'd use Space.
#include <QtWidgets>
int main(int argc, char ** argv) {
QApplication app{argc, argv};
QWidget w;
QVBoxLayout layout{&w};
// Individual Buttons
QPushButton p1{"button1"}, p2{"button2"};
for (auto p : {&p1, &p2}) {
layout.addWidget(p);
p->setFocusPolicy(Qt::StrongFocus);
}
// A button box
QDialogButtonBox box;
for (auto text : {"button3", "button4"})
box.addButton(text, QDialogButtonBox::NoRole)->setFocusPolicy(Qt::StrongFocus);
layout.addWidget(&box);
w.show();
return app.exec();
}

Answer 2

I tried it out on KDE/Ubuntu. It works automatically.
main.cpp
#include <QApplication>
#include "mainwindow.hpp"
int main(int argc, char** args) {
QApplication app(argc, args);
MainWindow m;
m.show();
return app.exec();
}
mainwindow.hpp
#ifndef MAINWINDOW_HPP
#define MAINWINDOW_HPP
#include <QMainWindow>
class MainWindow : public QMainWindow {
Q_OBJECT
public:
MainWindow();
};
#endif // MAINWINDOW_HPP
mainwindow.cpp
#include "mainwindow.hpp"
#include <QPushButton>
#include <QVBoxLayout>
MainWindow::MainWindow() : QMainWindow() {
auto* w = new QWidget;
auto* l = new QVBoxLayout;
auto* p1 = new QPushButton("ok");
auto* p2 = new QPushButton("exit");
l->addWidget(p1);
l->addWidget(p2);
w->setLayout(l);
setCentralWidget(w);
}
a.pro
TEMPLATE = app
TARGET = a
INCLUDEPATH += .
QT += widgets
HEADERS += mainwindow.hpp
SOURCES += main.cpp mainwindow.cpp
QMAKE_CXXFLAGS += -std=c++14
Edit: Apparently the buttons switch focus, but pressing enter does nothing. I guess you have to use focus-related mechanics (search for "focus" in the QWidget documentation) and implement it yourself. Or have a look at QDialog (as a replacement for QMainWindow in my example). It should have some meaningful default behavior for the enter and escape buttons.
Side note: Maybe you rather want to use the QDialogButtonBox for ok- and exit-buttons in your project. It's the cross-platform way of displaying OK/Cancel/Accept/Reject/... buttons because their arrangement differs between platforms. And this class can help you with that.

Answer 3

It is easier than all that code. Just use setFocusPolicy with Tabfocus on both buttons like this:
yourButtonOk->setFocusPolicy(Qt::TabFocus);
yourButtonExit->setFocusPolicy(Qt::TabFocus);