Given this example:

TextField {
    text: '1990'

    onFocusChanged: function(focus) {
        if(focus) {
            selectAll();
         }
    }
} 

In 6.4.0 beta 1 you could do selectAll in a onFocusChanged when it was triggered by a touch screen.

In 6.4.0 beta 3 is does not work anymore. Text does not get selected when touched on a touch panel. It only get selected when I click on it with a mouse.

As workaround I do selectAll in a setTimeout like function.

setTimeout(selectAll, 1)

where setTimeout is inspired by this answer https://stackoverflow.com/a/56014403

Then it works again.

EDIT:
the onFocusChanged signal is received and focus is true. It really is selectAll that does not have an effect.