I have copied and pasted text I started on the forum, and stuck it into note pad, and "built" my post off line and then copied that and stuck it into a fresh post window.
I found some grief with picture HTML when using MS Word though-- actually what seems to work well for me, I open a blank window in my Windows live e-mail, as if composing an e-mail to someone. I can spell check it, etc., and paste Photobucket code into it as I compose- and then just copy the whole bit and paste it into a blank forum screen.
When I try that with MS WORD it seems to booger with the Photobucket code.
Just what worked for me.