Qt Widgets: how to pay attention to a control?

Question

User interface

There was an error in the program: pay attention to such and such a control!
What are some interesting ways (in Qt5 Widgets) to poke a person's nose into one element or another?
Well, for example, a balloon tip ...

Answer 1

You can tritely set a border through QSS:
pWgt->setStyleSheet("border: 1px solid red");