How to create QDialog with QT Creator and connect it to the source?

[Zlatomir]

You are using uninitialized pointer in there, your slot should look like this:

void Imoti::on_pushButton_clicked()
{
    about *one = new about(this); //use a pointer and then create the object and allocate memory with new
    one->show(); //non-modal
}

void Imoti::on_pushButton_clicked()
{
    about *one = new about(this); //use a pointer and then create the object and allocate memory with new
    one->show(); //non-modal
}

To copy to clipboard, switch view to plain text mode 

or, in case you want modal:

void Imoti::on_pushButton_clicked()
{
    about one(this); //create a object directly 
    one.exec(); //modal dialog
}

void Imoti::on_pushButton_clicked()
{
    about one(this); //create a object directly 
    one.exec(); //modal dialog
}

To copy to clipboard, switch view to plain text mode 

LE: added 'this' as a parent for modal dialog too...