I think this would be a good addition when posting in the forum.

It seems redundant when you can go back and edit every single post you ever make. The forum itself acts as a preview.

I agree with Robin,
You can edit every forum entry you make or have ever made, simply by waiting to be redirected to the forum, and checking your post.
Simply hit the edit button, and edit it.
You can even delete all those posts that the image just didn't show up, along with all the "opps.... why isn't it working ones...."
when you eventually figure it out....... :-) :-) :-)
And you can even delete all those double post from the impatient ----I'll keep clicking the submit button........ when it isn't fast enough for me :-) :-) :-)
But most important, you can even read your post BEFORE you hit the submit button.