Edit Word misbehaves on adjacent regions delete #257

1. Create a document with these 5 symbols: aabab
2. Select first a: [a]abab.
3. Press Ctrl+Tab. There are now 3 editable regions: a a (b) a (b).
4. Press | - now the document is ||b|b (still in Edit Mode, first | selected).
5. Press Backspace - now the document is |bb (and still in Edit Mode).
6. Press + - now the document is +|b+b.
7. Press Esc - now the document is a|bab.

The problem is at step 5: the document must be bb because the remaining | is an editable region number 2 but for some reason after step 5 it "falls out" from the editing and subsequent modifications no longer affect that region (hence step 6 - +|bb+ instead of the expected ++b+b, and step 7 - expected aabab).