I'm using Floatbox v3.51 and I'm opening a Floatbox window using the following onclick event:

<input type='button'
value='View Member Profiles'
class='functionButton'
onmouseover="this.className='functionButtonHover'"
onmouseout="this.className='functionButton'"
onclick="fb.start({href:'memberProfile.php?form=memberProfileForm&formToken=9505e02fb1593d412f2afb626f16b692&forumId=1&memberId=100', rev:'width:750px; height:100%;'});" />

After the onclick event fires, the Floatbox window opens fine and the forms that I display and process in the Floatbox window function perfectly. Even the browser forward and back navigation buttons work for the Floatbox window content, except when I browse past the beginning of the window content. At this point, instead of the Floatbox window closing, the Floatbox window blanks out and displays the loading icon indefinitely. Is this normal, or am I doing something wrong?

Yeah, it's normal. When an iframe is first loaded into floatbox, its source is set to that spinning loading gif, so that's the first entry in the browser's history list for that iframe.

But note that browser back-button behaviour is screwy and inconsistent in different browsers. Some browsers, when you hit that back button, will navigate the top page back one in its history (Safari, Chrome for sure), while others will navigate the iframe content back. This behaviour is independent of whether the iframe is in floatbox or embedded on the page, and there is nothing we can do about it.

Thanks so much for your quick response!