Trackpad support has been improved in master for the Acer c720 chromebook when running DragonFly. Trackpads on other intel-based chromebooks when running DragonFly might work too but would possibly require more messing around with drivers. Other laptops... depends on their chipsets but the driver I wrote only operates with the Cypress APA trackpad via the I2C bus, and some work would probably be needed even on other laptops using the same trackpad chip.
I've been working on my Acer c720 and have made some improvements to the trackpad to make button emulation work better. In xorg.conf, the mouse protocol can now be set to "imps/2" instead of "ps/2" in order to get z-axis (mouse-wheel emulation) support. The three-finger sequence for the left mouse button emulation has been expanded to allow left, middle, AND right button emulation depending on which of the three fingers you set down last / and-or tap. There is one quirk. If you have three or more fingers set down exactly horizontally the trackpad gets confused and will generate bogus finger-up/finger-down events. It is best, when using three-finger sequences, to have your fingers placed on a slight diagonal. There is nothing I can do about the issue, the trackpad itself is reporting bogus data. Here is a full list of features I have implemented in the driver: FEATURES Jitter supression - Implements 2-pixel hysteresis with memory. False-finger supression- Two-fingers-down does not emulate anything, on purpose. False-emulated button handling- Buttons are emulated when three fingers are placed on the pad. If you place all three fingers down simultaniously, this condition is detected and will not emulate any button. Slider jesture - Finger the right hand side and slide up or down. (Three finger jestures) left button jesture - Two fingers down on the left, tap/hold right middle button jesture- Two fingers down left & right, tap/hold middle right button jesture - Two fingers down on the right, tap/hold left (you can also mouse the pointer with one, two, or three fingers. Placing three fingers down simultaniously will not emulate any button press. You can then lift and tap one of the fingers for the button press. track-pad button - Tap/push physical button, left, middle, or right side of the trackpad will issue a LEFT, MIDDLE, or RIGHT button event. track-pad button - Any tap/slide of more than 32 pixels and pushing harder to articulate the trackpad physical button always issues a LEFT button event. first-finger tracking- The X/Y coordinates always track the first finger down. If you have multiple fingers down and lift up the designated first finger, a new designated first finger will be selected without causing the mouse to jump (delta's are reset). -Matt