In this recent post I described a way to open your Contacts in a separate browser tab.
A similar thing can be done for Google Tasks. The situation here isn’t quite so frustrating, as you can at least open a popup window without losing your mail view:
However, the popup is small, and to do anything serious you really need to pop it out to a full-page interface using the ‘arrow’ icon above the task list. A quicker way is to simply visit
and create a browser bookmark.
The full-page Tasks interface is then available whenever you need it.