[sugar] frame auto-visibility configuration

[Eben Eliason]

On Wed, Sep 24, 2008 at 10:52 AM, Erik Garrison <erik at laptop.org> wrote:
> Hello all,
>
> On tabbing we are currently auto-toggling the frame.  Are we sure that
> this is necessary?  Could we include a configuration option to change
> this?

I disagree that showing the Frame is a bad idea.  It emphasizes the
purpose of the top edge of the Frame, and provides context while
tabbing so that it's easy to see where you want to "get to".

> Drawing the frame animation during tabbing robs us of processor right
> when we need it, slowing the perceived transition time between windows.

Drawing the Frame does take a little effort, it's true.  Compositing
support should later speed this up a good deal.  The current
reveal/retraction rate of the Frame is at least 2x as slow as I'd like
it to be, in practice.  Additionally, there *is* a lag on switching
windows, and this is, actually, part of the reason that I think the
Frame should be shown.  Without the Frame, we are forced to expose
each window in the tabbing process, which injects delays into each
tabbing event.  With the Frame shown, we delay the actual window
switch slightly so that it's possible to tab quickly past a few
activities you're not interested in, pausing only at those that you
want to see in more detail.

> Furthermore, as the XO only has one processor the frame animation (which
> requires available processor to run smoothly) will skip a lot of frames
> if the processor is loaded.  As we're auto-saving and re-rendering the
> windows of every window we pass during tabbing, the processor is

Saving and re-rendering...could you elaborate?  As I mentioned, the
point of using the Frame is to *minimize* the number of context
switches that need to happen.

- Eben

> invariably quite loaded, and the frame draw consequently is quite
> clunky.
>
> The attached patch to sugar optionally disables frame appearance if
> the file /home/olpc/no-frame-on-tabbing exists.  This is just a
> proof-of-concept hack to make it easier to quickly enable and disable
> the functionality and observe the performance change.
>
> I have created a trac ticket: http://dev.laptop.org/ticket/8633
>
> Erik
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