problem

See attached video.

reproduction (in chrome)

1. Edit a segment, in the example "PHP Manual"
2. Add at the end of the segment new Text with a leading space which gets then an INS tag. In the example " ASD".
3. save the segment
4. edit the segment again
5. double click on the added text "ASD" to select it
6. Then type a new word "FOO" intended to overwrite "ASD"

Expected result: "PHP Manual<ins> FOO</ins>

Received result: "PHP ManualF<ins>OO</ins>