What is the difference between Full Windows Touch Support and Limited Touch Support?
In the System control panel and in the PC Info section of the PC & Devices section of PC Settings, your device’s pen and touch support can be reported in a variety of ways. Here is the matrix:
|No touch||No Pen or Touch Input||Pen Support|
|Single touch||Single Touch Support||Pen and Single Touch Support|
|Limited multi-touch||Limited Touch Support with N Touch Points||Pen and Limited Touch Support with N Touch Points|
|Full multi-touch||Full Touch Support with N Touch Points||Pen and Full Touch Support with N Touch Points|
The meaning of No touch and Single touch are clear, but if a device supports multiple touch points, what makes the system report it as having Limited versus Full touch support? A device with Full touch support is one that has passed Touch Hardware Quality Assurance (THQA). You can read about the Windows Touch Test Lab (WTTL) to see some of the requirements for full touch support. If you have a touch device without full touch support, then Windows will lower its expectations from the device. For example, it will not use the timestamps on the device packets, and it will increase the tolerances for edge gestures.
Note that if test signing is enabled, then all multitouch drivers are treated as having full touch support. (This lets you test your driver in Full mode before submitting it to THQA.)