Overriding paintEvent broke window minimizing from taskbar

[jsulm]

@loginmen Has nothing to do with paintEvent.
Remove "Qt::FramelessWindowHint | Qt::WindowSystemMenuHint" and you will see that it works.

[loginmen]

@jsulm

QWidget mainWindow {};
    mainWindow.setWindowFlag(Qt::FramelessWindowHint);

Minimize fine, if do that

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint) {
//...
}

not working, but

Window::Window(QWidget *parent)
: QWidget(parent) {
setWindowFlag(Qt::FramelessWindowHint);
//...
}

work fine too, why?

[jsulm]

@loginmen https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
"Qt::WA_TranslucentBackground 120 Indicates that the widget should have a translucent background, i.e., any non-opaque regions of the widgets will be translucent because the widget will have an alpha channel. Setting this flag causes WA_NoSystemBackground to be set. On Windows the widget also needs the Qt::FramelessWindowHint window flag to be set. This flag is set or cleared by the widget's author."

[loginmen]

@jsulm some error in message Qt::FramelessWindowHint instead of Qt::WA_TranslucentBackground

[jsulm]

@loginmen What error?

[loginmen]

@jsulm in the message wrote the wrong flag

[jsulm]

@loginmen Sorry, I don't understand what you mean. Please rephrase. Show code and exact error message.

[loginmen]

@jsulm correct message:

QWidget mainWindow {};
    mainWindow.setWindowFlag(Qt::FramelessWindowHint);

Minimize fine, if do that

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint) {
//...
}

not working, but

Window::Window(QWidget *parent)
: QWidget(parent) {
setWindowFlag(Qt::FramelessWindowHint);
//...
}

work fine too, why?

[J.Hilk]

@loginmen

 Window::Window(QWidget *parent)
 : QWidget(parent, Qt::WindowFlags() | Qt::FramelessWindowHint) {
//...
}

[loginmen]

@J-Hilk still not working

[JonB]

@loginmen
One thing just to verify: parent is being passed in as nullptr to your constructor, right?

[loginmen]

@JonB That's right, he is the main widget (window), all his other children

[JonB]

@loginmen
OK. if you say one works and one does not: on the first line in the constructor-argument one or the line after the setWindowFlag() one try printing out what's in windowFlags() and compare for any differences?

[loginmen]

@JonB in constructor i have flags:

00000801

and in use function:

8800F801

flags decode:

80000000 WindowFullscreenButtonHint
08000000 WindowCloseButtonHint

00000001 Window
00000800 FramelessWindowHint

0000F000:
00001000 WindowTitleHint
00002000 WindowSystemMenuHint
00004000 WindowMinimizeButtonHint
00008000 WindowMaximizeButtonHint

If i use

Window::Window(QWidget *parent)
: QWidget(parent, Qt::FramelessWindowHint | Qt::WindowMinimizeButtonHint) {
//...
}

Minimize work fine and button not showing