Problems with preview scan and Umax backend solved

It seems, that the problems with preview scans and the Umax backend (scanner models Astra 2200/1220) could be solved (thanks to Oliver Rauch and Dr. Andreas von Heydwolff for bughunting/testing).
Please patch the file qscanner.cpp (under quiteinsane-0.2-alpha/quiteinsane) with the file qscanner_cpp_0_2_alpha_patch.
("patch qscanner.cpp qscanner_cpp_0_2_alpha_patch")
You can find the patch on QuiteInsanes project page (->Download).

Nevertheless, be careful when you try a preview scan for the first time !!

Error description:
QuiteInsane was using the smallest resolution supported by the device for preview
scans. In case of the Umax scanners, this means a resolution of 1 dpi. Unfortunately,
fullsize scans with such a small resolution make the scanner move beyond it's
end-position, which causes an awfull noise and might even damage the hardware.
(...and a preview with a resolution of 1 dpi also is quite useless)
The patch ensures, that a preview resolution of at least 50 dpi is used.

Please try and tell me your results !
Thank you