[webkit-help] CSS display vs. visibility regarding performance and memory

[Sebastian Werner]

Hi!

I am a developer of the qooxdoo RIA framework (client side JavaScript
framework with own GUI toolkit). We are currently investigating if
it's better to use "visibility" or "display" in our framework. We had
an issue with "display" as it leads to reloading of embedded Flash
movies when toggled (e.g. movie is placed inside a TabView). So we
thought that visibility might be an alternative. This would work as
our widget system renders most elements with position=absolute and
overflow=hidden.

Interestingly the reloading of Flash movies does not happen when using
visibility. But there might be a caveat. Do browsers, or Webkit-based
once to be more specific, do any kind of memory deallocation when
hiding elements using display=none? In complex GUI there are often
several parts which are invisible. Think of tab views, MDI interfaces,
popup dialogs, etc. These elements are removed completely from the
document flow so it might be a logical behavior.

It might be interesting for all Ajax developers what the differences
between removeChild, display=none, and visibility=hidden is -
regarding performance and memory aspects.

As such things are not easily benchmarkable, I really hope to get some
insights from the developers here. Thanks for your help.

Regards,
Sebastian