When working on issues for this module, I noticed that the fresh of the preview was sometimes slow. Also, there is sometimes a noticeable wipe and the page with its white background is refreshed within the settings tray, which defaults to having a dark background.
Having too many tabs open in Chrome may have been an aggravating factor in making this more obvious, but we should expects users in the wild to be using this functionality across various levels of hardware.
After the initial load, have an option to only refresh part of the page, for example the content region. Doing so would allow Drupal to render faster (since it wouldn't need to re-render blocks unlikely to change) and might avoid effects like the visible wipe and losing scroll position.
I think there should be an option to disable this selective behaviour because some sights might have parts of the node data displayed outside the content region.
- Determine an appropriate / optimal strategy to partially refresh the page. A couple of strategies are discussed at
https://drupal.stackexchange.com/questions/19934/every-five-seconds-with...
Add a way to either enable/disable this partial refresh strategy, or perhaps select which regions to refresh. This could be via localStorage, a user setting, or a site setting.
Postponed
1.0
Code
Postponing - I think this would be something we'd look at addressing as part of our 3.x plan. Figuring out a way to achieve a truly live preview likely requires a partial refresh of some kind.