You can set the style sheet for the application, or for the parent of those line edits:
window()->setStyleSheet("QLineEdit { border: none }");
or
window()->setStyleSheet("QLineEdit { qproperty-frame: false }");
The latter is equivalent to executing the following code:
for(auto ed : window()->findChildren<QLineEdit*>())
ed->setFrame(false);
The window()
refers to QWidget * QWidget::window() const
.
Since you want to do it application-wide, you can simply set the style sheet on the application:
qApp->setStyleSheet("QLineEdit { qproperty-frame: false }");
You can further use CSS selectors to override the frame on certain objects. You've got the power of CSS at your disposal.