[Update: June 14 2011]
This is no longer needed starting with Mari 1.3v1, where the wacom detection was fixed. In fact using the here described workaround with Mari 1.3v1 and up breaks the wacom functionality.
So if you are using mari 1.3v1 and up do not follow these instructions !
[End of Update: June 14 2011]
If you are running Mari under a recent linux distribution and happen to have a wacom tablet, you certainly run into the problem, that pressure sensitivity does not work in Mari.
I encountered this problem during my normal evaluation period and almost went mad, that such a basic need wasn’t working. I knew that Mari was Qt based and that Qt had increasing problems recognizing tablet input devices with newer versions of the xf86-wacom driver.
As it turned out, the qt version Mari is using ( 4.5.2 if I am correct) does a somehow hardcoded approach in finding the available input devices. That means it expects the wacom driver to name its devices “stylus”, “eraser”, “pad” etc.
With the new version of the wacom x-driver that started shipping with ubuntu 10.04 the way the driver names the devices has changed, and whatever tricks you try to name them (either through xorg.conf or the fdi naming) you never will get a device called stylus.
I had a look at the Qt code and it actually looks for a device starting with stylus.
A run of xsetwacom –list gives the following output on my machine:
Wacom Intuos4 6x9 eraser ERASER Wacom Intuos4 6x9 cursor CURSOR Wacom Intuos4 6x9 pad PAD Wacom Intuos4 6x9 stylus STYLUS
My way of fixing this was to actually patch the x wacom driver and prepend the desired names in front of the device name instead of appending it. So my output from xsetwacom –list looks like this:
eraser Wacom Intuos4 6x9 ERASER cursor Wacom Intuos4 6x9 CURSOR pad Wacom Intuos4 6x9 PAD stylus Wacom Intuos4 6x9 STYLUS
With this Qt ( and thus Mari) is able to find the wacom input devices and works just fine.
This problem was fixed in a later qt 4.5 version and should be fixed for Mari just by using a later version (which may pose different problems ). I guess its just a matter of time until Mari will be using an updated Qt version.
And here is my patch against the current xf86-input-wacom driver (version 0.11.0).
And here is my compiled wacom driver: 64bit Kubuntu 11.04.