How to make a mainwindow as earlier after making it transparent

[Niamita]

Hi all

I want to make my background transparent when clicked a button and after clicking on another button i want to make background as it was earlier. I try

this->setStyleSheet("background:transparent");
this->setAttribute(Qt::WA_TranslucentBackground, true);
this->setWindowFlags(Qt::FramelessWindowHint);

this->setStyleSheet("background:transparent");
this->setAttribute(Qt::WA_TranslucentBackground, true);
this->setWindowFlags(Qt::FramelessWindowHint);

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and

this->setStyleSheet("background:transparent");
this->setAttribute(Qt::WA_TranslucentBackground, false);
this->setWindowFlags(Qt::FramelessWindowHint);

this->setStyleSheet("background:transparent");
this->setAttribute(Qt::WA_TranslucentBackground, false);
this->setWindowFlags(Qt::FramelessWindowHint);

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but not getting desired result.
What i am doing here.
Waiting for yours response.