how to read-only fields to add and edit page?

go to the visual editor and double click on field that you want to display as read only, and than from left side select read only feature...

Thanks for your reply. I guess I was not happy in my question

How would one read-only field that could be filled in automatically depending on another field. For example:

If a field A = B = Field 10, if field A = B 2 = Field 20;
How would the hidden field?

João

I decided with the example below
var ctrl = Runner.getControl(pageid, 'Make');
ctrl.makeReadonly();
http://xlinesoft.com/phprunner/docs/makereadonly.htm