When Xorg 1.4.2 first boots it shows a squashed screen on a WinmateR15T63
Workaround
One workaround is start X attached to a different Dell1504FP monitor. Then switch back to the touchscreen. Now the display takes the full width. (?)
Resolution detection bug?
I assumed it had to do with the screen resolution being mis-detected by Xorg. However both images are reported being displayed by the monitor at 1024x768!
However on closer inspection the Winmate T15 T630 Xorg.log shows
(II) intel(0): Output VGA using initial mode 1280x768
It seems like the monitor was lying and it really was a screen resolution detection problem!