Fix touch offset

[matham]

This fixes the slight vertical offset of the touch on a Windows 7 touch screen by including the caption bar.

[tito]

Seems correct, but it must be tested on others platforms to ensure that it's not breaking current app too.

[tito]

@hansent Do you have the possibility to test that PR ?

[tito]

If any peoples complain about it, we need to figure out what's the difference with and without this issue.

it-digin tools got also the issue, and i've seen it during europython.
The issues doesn't appear if you connect an external hardware.

[jneb]

Same problem on my Android: touches appear too low when there is a status bar.
I traced it back and found that the touches are wrong, not the coordinates of the widgets. You even get negative y coordinates at the lower edge of the screen.
Offset is indeed (about) equal to the status bar height (38 pixels in my case: AT-AS45Q, Android 4.4).

[jneb]

Oh yes, forgot to mention: Qpython 0.9.4, Play 0.9.8.5,

[tito]

Please open or see with QPython, not here :/

This issue is for windows provider, and has nothing to do with Android.
I head about QPython issue, but we are not part of the project, and don't know how they ship/work with all the libraries. We don't have the issue here if you use directly Kivy and Python for Android.