Hello Dennis,
Thank you for the idea. It is not very meaningful to have a "middle" drop position in the context of the default TabbedWindow behavior because it doesn't support automatic merge of the contents. However, it might be a good idea to allow customizing the size and the position of the drop indicator visual. This is why we have approved this feature request. The Unplanned status means that we agree that the feature is meaningful for the control, but it is not yet planned.
In the meantime, you can find attached a project showing a customization that could be useful in your scenario. I hope this helps.
Regards,
Martin Ivanov
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