I've managed to style my QLineEdit to something like this:

void Utilities::setFormErrorStyle(QLineEdit *lineEdit)
{
    lineEdit->setStyleSheet(
            "background-color: #FF8A8A;"
            "background-image: url(:/resources/warning.png);"
            "background-position: right center;"
            "background-repeat: no-repeat;"
            "");
}

I called the function using

Utilities *util = new Utilities;
util->setFormErrorStyle(lineNoStaf);

The flow should be something like this:

1. User open form
2. User fill data
3. User submit data
4. Got error
5. Use setFormErrorStyle()
6. User edit the text in the QLineEdit and the style disappear

This function should be reusable over and over again, but how can I connect QLineEdit signal such as textChanged() to a function in other class that will reset the Style Sheet and then disconnect the signal so that it won't be running continuously every time the text changed ?