Backspace behavior in Midas html editor

Hi,

I am using Mozilla Firefox [Mozilla/5.0 (Windows; U; Windows NT 5.0; 
en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0)].

I was trying the midas demo available at: 
http://www.mozilla.org/editor/midasdemo/

If I type the following lines in the html compose area:
-----------------------
This is test line 1

This is test line 2

This is test line 3

This is test line 4
-----------------------

Then I select the 'View HTML Source' checkbox. 
Use the mouse to move the caret to '2' and press the backspace key.
I notice that the content being actually deleted is not where the 
cursor points. The deleted content is before the caret position.

Is this a known issue ? If so what is the bug number filed for it ?

Any help would be highly appreciated.

Regards,
Masaoud