Make an editable combobox widget #121
Description
In Add Axis or Edit Axes plugins it would be nice if user could type their own name for an axis. This would require a input widget that is a list that can be modified by user and is represented with an editable combo box.
To do this, we should improve the parameter infrastructure to support combo boxes; i.e., data with multiple choice, but where you can also enter your own value. In Swing, this is a JComboBox with isEditable=true.
We could use a boolean toggle in @parameter called e.g. allowCustomChoices, false by default, and if set to true, the ChoiceWidget would also function as a freeform text field.
Migrated-From: http://trac.imagej.net/ticket/1481