Select «all» in drop down box

Hi Experts

In our dashboard I am filling a dropdown box with some
values from a data source. I us the following script to fill the data.

DROPDOWN_1.setItems(DS_2.getMemberList("ZQMKPI",
MemberPresentation.INTERNAL_KEY, MemberDisplay.TEXT, 100, "No
KPI selected"));

So by default the drop down box will say “No KPI selected”.
Then the user can select a KPI from the dropdown box and everything is fine.
But in some rear cases I would like to set the selected item in the dropdown
box back to “No KPI selected”. How do I do that?

Kind regards

Erik