Click trapping is a good thing to prevent you from accidentally clicking on something while you only want to preview the output of your post. But I need to be able to click because I check related posts to see if I can add related internal links for currently writing post.

So, a quick solution:
" get rid of clickTrap of Blogger post writing preview
style yjlv.blogspot.com div.blogger-clickTrap { display: none }
or
" get rid of clickTrap of Blogger post writing preview
style [blog-name].blogspot.com div.blogger-clickTrap { display: none }
for non-custom domain blogs.

No add-on/plugin or whatsoever required, Vimperator/Pentadactyl makes things easier and fixes quick. One-liner, that's all. I used to remove it by using FireBug to delete that element, four clicks, I think.

I do think Blogger should offer an option to disable it, because not everyone is a fan of that. And I do prefer to check links by hovering over link anchors and read the status bar.

Also, on Blogger, you can code JavaScript in your blog post which is awesome for JavaScript topic bloggers, so some UI may be displayed and interaction is needed. Though this is very rare case, 99% people wouldn't code and I don't actually code directly on Blogger but with local file generated with reStructuredText. So this part doesn't cause trouble for me at all.