#41 Incorrect erasing of empty strings using Delete key

[Anonymous]

Scenario:
Try to type some text, then press Enter key some times (e.g. 7-8 empty strings), then type text again.
After that return the caret onto middle of empty lines and press delete, erasing these lines.

Expected result:
Lines should be deleted normally, like in others text editors.

Actual result:
Caret has abnormal behavior (jumps to different lines and so on)

Problem:
Incorrect Delete key processing during syntax highlighting.