Is there focus event for line edit?

[Lykurg]

Yeah, that was too fast. The right syntax should be

ui->edtFileName->installEventFilter(this);

ui->edtFileName->installEventFilter(this);

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in the c-tor of exportData.

Now i am capturing the mouse press event for the line edit object. But my only worry is that unnes=cessary control comes to this function on every event(apart from line edit events,which i wanted to do).

That's the sense of an event filter. No problem. You can alternative, instead of returning false, call the base class event handler.