Qt - minimizing and maximizing app without standard titlebar buttons - c++

Question

I have a Qt application where there is only one widget which is not a MainWindow, just a QLabel. It has not title bar (obtained through setWindowFlags(Qt::FramelessWindowHint)), thus the standard minimize and maximize buttons are not available. But there is a sidebar at the widget's side where we provide a minimize button that should behave as the standard minimize button.
How do I do it?
I tried the solutions at Minimizing a Qt application and Qt C++ minimize and maximize window. Neither works. I can hide the app of course, on clicking the minimize button. Problem is, how to restore it through standard mechanisms?
Scenarios:
On Mac, the dock icon is clicked. Thankfully, OS X native APIs can give me a notification when dock icon is clicked, so based on that, I can unhide the widget and make it active.
On Mac, the app icon is double clicked in /Applications, or clicked in Launchpad. How do I get a notification for this? The code doesn't even come to the main.cpp that I can unhide it from there if it is hidden.
On Windows, the application icon in the taskbar is clicked (the app does not have a tray icon). How do I get notification for that and unhide it?
On Windows, the app icon is double clicked either in Program Files, or may be a desktop shortcut icon. How do I get notification for this to unhide it?
If this aproach is not correct, how do I show and hide the app as per standard behavior on both Mac and Windows?
Platform - Qt 5.3.1, 32 bit.

Answer 1

This is not an answer, but it might help sorting out which events are triggered (points 1,2 and 3).
#include <QApplication>
class newapp : public QApplication {
Q_OBJECT
public:
newapp( int &argc, char **argv ) : QApplication(argc, argv) {}
protected:
bool event(QEvent *ev) {
std::cerr << "APPLICATION EVENT " << ev->type() << std::endl;
return QApplication::event(ev);
}
};
and in your main.cc you will have
newapp myapp(argc,argv);
instead of
QApplication myapp(argc,argv)
Once you identify the events triggered, you're almost done: you need to tell to you newapp to restore the size of the Qlabel (there are tons of ways to do this, so provide your implementation and you might get more focused help)
For point 4, it's something else due to the different behavior between OSes as in Windows double clicking for the second time an app, will launch another instance of the application (on OSx it will raise the first opened app). You might find something that suit you in this project HERE