How to close the dialog using close(X) button or cancel push button?

[ChrisW67]

Groan. Please read at least a few pages of the documentation and try something for yourself before asking how you can implement default behaviour (the close [X] widget) or behaviour that is adequately covered in the QDialog manual page and any number of the bundled examples.

You want QDialog::reject() to "cancel" the dialog, or QDialog::accept() to "OK" the dialog.