Comment 12 for bug 381884

What if you do the following:
1) Put your left finger on the left half of the trackpad
2) 1 second later, put your right finger on the right half of the track pad

Does this cause a jumping of the cursor? If so, this is what would cause the
scrolling issue. If not, the two-finger scrolling issue may have been
fixed.

The second problem is the smoothing of the cursor over the sensors that are
present in the trackpad by the driver. If you were to put the left side of
your index finger on the trackpad and slowly roll it to the right so that
the right side of your finger touched the trackpad, the mouse should barely
move but in a very smooth way. Currently this isn't exactly what happens
and (at least for me) precision use of the trackpad is next to impossible
and causes my hands to cramp up in about 5 minutes. I have to use a mouse.

Thanks for the feedback!

Blaine

2010/4/13 Νίκος Αλεξανδρής <email address hidden>

> I cannot confirm this behaviour on the Macbook Pro 5,1 (currently using
> Kubuntu 9.10/ 64-bit with mactel support). Scrolling with two fingers is
> smooth here.
>
> --
> Appletouch touchpad driver produces jumpy two-fingered scrolling
> https://bugs.launchpad.net/bugs/381884
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in The Linux Kernel: New
> Status in Mactel Support: New
> Status in "xserver-xorg-input-synaptics" package in Ubuntu: Confirmed
>
> Bug description:
> Binary package hint: xserver-xorg-input-synaptics
>
> My system is: Linux richard-laptop 2.6.28-11-generic #42-Ubuntu SMP Fri Apr
> 17 01:58:03 UTC 2009 x86_64 GNU/Linux. However, this issue applies to at
> least Intrepid and Jaunty, 32 and 64 bit, running on Apple Mac hardware that
> uses an Appletouch touchpad. It has also been reported in the Gentoo and
> Debian forums.
>
> >From what I can find on the Net, the Appletouch touchpad was first used in
> February 2005 for the G4 aluminium PowerBook, and last used for the Macbook
> Pro in its 3rd generation, then 4th generation Intel Macbook in early 2008.
>
> The issue is with two-fingered scrolling. The Appletouch features the
> ability to detect two (or three) touches. OS X uses this feature to enable
> scrolling, similar to a scrollwheel on a mouse.
>
> The synaptics driver causes the simulated scrollwheel to start moving as
> soon as one places a second finger on the touchpad. That is to say, placing
> a second finger causes the trackpad driver to deliver scrolling signals,
> which means that attempts at vertical scrolling feels jumpy, or over
> sensitive.
>
> There was an update to the OS X driver that fixed this situation for Apple.
> I guess that it detects the second finger and programmatically ignores the
> first few scrollticks, thereby 'deadening' the output. This is what we
> need.
>
> The synaptics driver allows for some modification, but not for multitouch
> input. This needs to be fixed at source code level.
>
> Richard
>
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