Adding Select All or Deselect All option in drop down list button

I am using a drop down button for Enumeration list. Is there any way to add select all and deselect all option for selection? I know multi selection option is available but I need select all and deselect all. any clue?
1 answers

An enumeration always has one value:

What you want is therefor impossible. Instead you should create a *-* association with another entity. That entity should contain objects with the enumeration values as description. This way you can select more than one.