We discovered yet another oddity with the X2O client on IE. Here was the first oddity discovered in November. This oddity seems to occur on Internet Explorer 8, Release Candidate 1. Thanks to Kevin for finding the bug for us. When he tried to login on IE8RC1, he'd hit an error page.

Why?
Apparently there is an issue with using the ImageButton object. We use ImageButtons on the X2OClient. The first one you see is the Login button.

If you happen to click on certain spots on the button where the X and Y coordinates of the spots aren't integers (e.g. X = 42.7), the framework throws a runtime error:

Input string was not in a correct format.

Yep. Apparently, with ImageButtons, part of the callback involves passing the x-y coordinate position of your mouse button (I don't know why offhand, my guess is it has something to do with ImageMaps - something I haven't used since 1998) to the server. That's fine, except that the framework automatically assumes these are integers.

On most browsers, there isn't an issue, as the postbacks always resolve to integers. But, it looks like on the new IE8 release, they're getting more particular and passing back decimals.

What's the workaround?
If you're using IE8RC1, the workaround is to tab to the button and hit ENTER, rather than clicking on it with your mouse. We fully admit, this is a sucky workaround. But, it'll suffice until we can get the next update released. Or, you can use another browser.

In a future update, we'll likely strip out the ImageButton and put in regular old HTML buttons. This is something Mustafa suggested months ago (not for this particular reason), but I didn't listen. Thank you Microsoft!