small in-line widgets - odd behaviour across line /para break

Hi - I have created some small 'widgets' based on the <strong> tag - these are used as tokens in doc templates. All is working perfectly apart from behaviour across lines...

If I have tagA on line 1 with a few characters after it and tagB on line2 ( either <br/> or <p> ) - as I delete characters on line1 I would expect tagB to eventually jump back up to the first line. However it gets deleted  - when I use a regular strong tag ( not a widget class ) it behaves as expected.

Is this a bug or have I missed something?