
Wants to write a Firefox extension to make reading Gmails even easier (now there are Gmail Conversation Preview, Gmail Macros and many more) by seeing emails and reply at the same time. This needs to split the view the tab so that one views the email received and another views the reply to that email currently being composed. Scrolling any view must not affect the position of another. This way, the questions in the email can be answered one by one easily.
The first splitting ability I came across was found in popTart, but it only works for Digg. Then, I noticed Tricky Frames and Split Pannel (deliberate typo?!). The most promising extension available is Content Holder from lots of extensions unlisted on the official Mozilla Add-ons.
They are not very suitable for the Gmail reading purpose and are not quite well developed. All but Split Pannel supports only up to FF1.5. They all load separate pages in each view, but maybe splitting only the view of the same page, like Word of Acrobat, is a better idea.