This ensures that the bubble does not flicker in and out as the user's mouse traverses many links, and allows users to see the targets of multiple links quickly (compare to a tooltip solution). Timer A should be high enough so that if the user's cursor doesn't accidentally trigger the bubble in normal navigation, but low enough so that a user who wants to see a link is not kept waiting - generally with a slower fade-in, Timer A can be pretty low.
The status bubble's width is fixed to a percentage of the width of the window - while this results in link truncation, it prevents resizing as the user moves the mouse over multiple links. We try to keep the bubble under half the width of the window so that the bubble feels anchored to a corner, making that corner the obvious target for the user's eyes.
Note that the status bubble is trivial to spoof using a little CSS.
In addition, it is also trivial to swap out the link after the user has hovered over it and pressed it, but before navigation. (In fact,
Therefore, the status bubble is just a convenience for users hovering ove links on well-behaved sites, but it is not a security surface.
User Experience >