Built-in editor in 2.5 messes with space and tabulations inside of pre

I paste a lot of C code into my posts. After upgrading to 2.5 I found that I cannot do it anymore. There are several problems actually.

First, pressing TAB keyboard button to add indentation no longer works – it moves the cursor somewhere out of editor.
I’ve seen this problem in Firefox 2 (2.0.12) and Firefox 3b4. Pressing the TAB does work in IE 7, but it reports javascript error and works from second attempt (i.e. pressing TAB twice, adds one character).

Second, even if I copy/paste the C code from somewhere else with tabulation symbols inside, after saving they’re all gone.
Again, this problem occurs in Firefox only. IE 7 handles this.

Third, if adding indentation with space characters, as with tabulation, spaces are gone after saving.

I’ll appreciate any help with this issue.
Thanks.