If you use Firefox to update your Joomla 2.5 website you will be experiencing a really irritating glitch when you upload a photo.  No matter where you place your cursor, when you upload the image it will be inserted at the top-left of the article.

You will also find that you cannot move the image until you have saved the article.

This is a Firefox bug, but there’s a simple solution.

Look for the file modal.css which you will find in media/system/css/modal.css

Place this additional CSS to the last line of the file:

@-moz-document url-prefix() {
 .body-overlayed {
 overflow: visible;
 }
}

That should solve the problem!