If I am not mistaken.
The quick reply in Photopost is the same as the quick reply in VB3 and if you use the Photopost comments script with WYSIWYG it performs like VB3 as in you hit the bold once and you can type bold text and then hit it again to stop
In the quick reply box you need to hit it once to open a bold tag enter your text and then hit it again to close the tag.
At least thats how it works on my site and geiri's as well as any VB3 site I have been too.
Even though I have had a VB
license for like 4 years I just recently converted my site to it about a week ago so I am still investigating all the little stuff