[Dillo-dev] Horizontal scrolling with mouse buttons

I have a Logitech wheel mouse which supports horizontal scrolling by pressing the scroll wheel to either the left or right. These actions generate mouse button events where the button is identified as either "6" or "7" respectively. Dillo handles these horizontal scroll events properly, but afterward the scrollwheel no longer works for vertical scrolling (the scrollwheel up/down events are reported as buttons "4" and "5" respectively); instead the scrollwheel results in left/right scrolling. I am running Dillo 2.2 on a Slackware system. Regards.