Cannot disable button

Forms
1

fd.control('prev_tabs').disabled = true;
fd.control('prev_tabs').text = 'I should be disabled now';

The second line of code correctly changes the text on this button, but the first line of code fails to disable the button. What am I doing wrong?

2

Dear @donald.kantik,
There is no disabled property for the button. You can simply remove the code that runs on button click:
fd.control('Button1').onclick = '';