The starter app includes a UI named 'Navigation'.
I wanted to pull that UI out of the app and put it into Themer.
It does not seem that that is yet possible.
At least until Tab or Tab-Panel is included on the list of available mixins/components when adding a UI in Themer.
Further, the 'Navigation' UI includes Bar as well as Tab components.
It does not appear that Themer currently supports creating UI's that leverage multiple mixins/components.
Am I understanding this correctly?