I have a Views exposed filter, that allows multiple items to be selected. It's based on the 'Allowed values' for a multiselect CCK field.
The exposed filter comes out looking like this:
Option 1 Option 2 Option 3
I need to add an 'All' option to the top, so that it would be:
All Option 1 Option 2 Option 3
Clicking the All option should have the same effect as holding Ctrl and clicking on Options 1, 2 and 3. ie. return all nodes that have a value of Option 1, Option 2 or Option 3 for this field.
How can I add such an option to my widget? I'm sure it could be done through form_alter somehow, but I can't suss out how.