We need a way to control when an action is completed (screenshot)

[PaulKinlan]

When taking a screenshot of webgdedeck.com it doesn't load in the content, I suspect this is because it is loaded after the 'load' event.

It would be nice to let the user configure when the action should take place in the page life-cycle.

[McFoggy]

as a side-remark for SPAs & off-line first webapps a standard page life-cycle event does not make that much sense, because much of the content is loaded asynchronously.
In this case perhaps that an application event is better suited (or any other mechanism).

[ebidel]

I think a waitFor=x param would be good. That maps well to pptr's API's which have a similar param that wait to resolve page.goto (and similar methods) by x milliseconds.