cp5: How do you make a text field auto-select the type when you click in the field

undertone

I've got a textfield that I've set to integer so that only numbers are allowable. But It's a bummer that when you click in the field, you have to hit delete several times to get rid of the old value before you input the new value. If... when you clicked in the field, the old value were already selected... you could just start typing the new value. But I'm not sure how you would accomplish this in cp5.