When text boxes such as dijit TextBox are set to readOnly, there is no difference from before setting. It is impossible to distinguish whether they are read-only from the appearance. So, a small adjustment was made to distinguish it from the editable text box.
After adjustment, the text box 
, list box
Implemented through css
.dijitReadOnly * {background-image: url("./image /lock.png"); background-position: right center; background-repeat: no-repeat; background-size: 16px auto; padding-right: 1px !important; }
Icon file