How to show pick list for a SelectItem based on some other event

[jay.l.fisher]

I've looked at a lot of posts asking this same question and still can't seem to find one with the answer. I want to force the pick list to be shown for a SelectItem when some event occurs other than the user clicking on selector. I've tried showPicker() which doesn't seem to do it. The javadocs for that are a little vague so I'm not sure if that is what that method is supposed to do since it seems to be tied to showPickerIcon.

Method to show a picker for this item. By default this method is called if the user clicks on a pickerIcon, shown by setting this.showPickerIcon to true. May also be called programatically.
Default implementation lazily creates a 'picker' from the set of defaults defined on this FormItem.

I've also seen an old post referring to a method on SelectItem to showPickList() which seems to be exactly what I need, but SelectItem has no such method.

[Isomorphic]

showPicker() shows value picker such as the DateChooser for a DateItem; it's unrelated to the pickList.

An API doesn't exist to show the pickList because to date all attempts to show it manually have been hacks that won't really work - what's the use case here?

[jay.l.fisher]

I probably should have added to this post. It is an attempt to address the same problem with dependent selects. When the user makes a choice in one SelectItem we need to force them to make a new choice in a second SelectItem. We can clear their previous choice in the second select, but that doesn't prevent them from ignoring the fact that it is now blank and saving the row/form. Clearing the editValue from the second SelectItem just reverts it to "unchanged" status, so when the save occurs, the old value remains.

[Isomorphic]

We've replied to the other post - let us know if this need to manually open the picklist comes up again.