This is possible by using the afteShowForm event of the grid – it gets fired immediately after the form is shown. Then, you can locate the element showing the field (the same ID as the column name) and hook the autocomplete logic to it.
Except that afterShowForm gets called each time the form is shown (!). Which would mean that you invoke autocomplete again each time the form is shown.
You can get around that by setting “recreateForm:true”, or you could use onInitializeForm, which only gets called once.
.
