the field "flags" of struct ScrollClass uses ScrollFlags as a mask
spec:
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/specs/XI2proto.txt#n802
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/XI2.h#n151
<field type="CARD16" name="number" />
<field type="CARD16" name="scroll_type" enum="ScrollType" />
<pad bytes="2" />
- <field type="CARD32" name="flags" enum="ScrollFlags" />
+ <field type="CARD32" name="flags" mask="ScrollFlags" />
<field type="FP3232" name="increment" />
</struct>