- Place the namespace bar below the "advanced parameters" bar
- Use OOJS' MenuTagMultiselectWidget (with placeholder) for input, so that namespaces are autosuggested to the user
- Have a checkbox which allows users to search in all namespaces.
- When the box is selected, add all namespaces as seperate bubbles in the input field
- When the box is deselected, remove all bubbles from the input field
- When the user deletes a bubble, but the box was checked, uncheck it
- By default, have "article" as a tag in the input box