In this forum and the GXT 3.x forums I use, I get the attachment icon, and if I click on the image icon I can include image "From Computer" or "From URL".
In the premium forum, the attachment icon doesn't exist (see screeshots below). Also, if I click on the image icon, I only get the "From URL" option for including images, I cannot include them from my computer.
I have verified this behavior in Chrome and Firefox. It has been this way for as long as I can remember (close to a year now).