Google is testing major user interface changes to its Gmail service that would affect the look of both the desktop browser-based and mobile versions.

The move is seen as an attempt to closer unify both versions and make Gmail available with full functionality across multiple screen sizes and resolutions.

Changes include a "fly-in" menu system that replaces the tabbed system which was implemented last year. Email will be sorted by topic, with some of those shown in the screenshots being travel, purchases, finance, social, and forums. There is also a Google Hangouts interface on the right hand side, which is collapsible. A large ‘+’ icon hovers down in the lower right corner that pops out for email composing and adding reminders.

Replacing Gmail’s star system, which allows users to highlight important messages, is a pinning system that allows emails to remain ‘pinned’ to the top of the inbox. Users get the choice of leaving these at the top or sorting them in a chronological order.

The reports first surfaced on Geek, which said there were no release dates for the feature update.