can not correct layout image which width over user's [screen_width - (left_sidebar+right_sidebar)]

Hmm, that's a difficult one.
I am currently tempted to mark this as "won't fix", as this is a very rare situation, and normally you don't want to display such large images inside a theme (the proper way would be to display a smaller image in the theme directly and then the bigger version in either a popup, a direct link or a javascript overlay window).

However, if someone has an idea on how to solve this, I'll be glad to review and integrate it!

If time permits, I might look into it myself, but that's not a promise at the moment ;)

better status

it isn't rare situation

this problem appears every time, when picture width + width of sidebar(s) is wider than user's screen

for example, layout of page is nice on 1280*1024 screen with image 640*480, but is wrong (like in header post) when user works with 1024*768 screen (see screenshot)

I'm not familiar with CSS - and cannot understand, why left block is shifted right instead of stay-in-place in left field.

well... one of possible solutions:

create new class in style.css

.scrcontent {
  width: expression(document.documentElement.clientWidth - 422);
  display: block;
  overflow: auto;
}

replace in node.tpl.php and comment.tpl.php <div class="content"> to <div class="scrcontent">

we'll get scrollable node's content, if it's width is more than central column width - and page still looks correct