Comment 135 for bug 151448

pkButtons is always 2.

https://www.winehq.org/pipermail/wine-devel/2007-December/061414.html
> That is, in X, our devices come out as 1 based (not 0 based), and
> on Windows, they report as 0 based. iow, with this patch, pkButtons is always 2;
> on Windows, it's always 1.

patch

https://github.com/wine-mirror/wine/blob/master/dlls/winex11.drv/wintab.c#L906

wintab.c - motion_event()

    gMsgPacket.pkNormalPressure = motion->axis_data[2];
- gMsgPacket.pkButtons = get_button_state(curnum);
+ gMsgPacket.pkButtons = get_button_state(curnum)-1;
    gMsgPacket.pkChanged = get_changed_state(&gMsgPacket);