Attribute type BOOL default as text problematic and bug showing current value

[ermbutler]

Using text "true" is setting it correctly, but not displaying the retrieved value (so it looks like it did not stick) Also- Text input was used intermediary to slider with unset option --> but enum will satisfy this an can be added instead.

[sbatchelder]

Any chance that it doesn't look like it's sticking because the actual localization is being secretly moved to a new/temporary "undefined" group? See #894