I'm trying to make "upload to imageshack" plugin. The concept is very easy:
1) Using the new Context API to get source url (that works great).
2) Get the contents of image through XMLHttpRequest
3) Now send them to Imageshack (or alike service)
4) Receive and store URL to uploaded image in clipboard.

And here comes the problem, it seems that javascript is not very good at receiving and handling binary data. If there are bytes which javascript is unable to interpret, it just replaces it with "%uFFFD" character, completely wasting the idea, there is just no more original data to send.
Is there some way to overcome this? For example, there are sendAsBinary and getAsBinary in Mozilla's XMLHttpRequest, which are perfectly suited to overcome this issue.