Hiding parts of QDialog

I changed from Qt 4.8.4 to 5.0.2, when I execute my application I get a warning about setGeometry: violating constraints of window,but the code doesnt even use setGeometry. The idea is that when I click a certain button parts of my dialog should hide, and the dialog size should change to suit the needs of the remaining contents. PLEASE HELP Here is the code,its actually a custom slot: void KeyBoardDialog::showHideKeyboard(){     if(ui->MainFrame->isVisible()){         ui->MainFrame->hide();         this->setFixedHeight(this->height()-320);         ui->pushButtonHideKeyBoard->setText("Show Keyboard");     }       else {         ui->MainFrame->show();         this->setFixedHeight(this->height()+320);         ui->pushButtonHideKeyBoard->setText("Hide Keyboard");     } }