[Bug 57990] Scrollbars of dotnet application always scrolls in both directions (horizontal and vertical)

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57990

--- Comment #5 from [e-mail] ---
It seems win32u/scroll.c is responsible for this task.
I did some debugging but till now the mouse move event seems to be valid.
"Vertical" is detected correct.

else if (msg == WM_MOUSEMOVE)
.
.
.
                send_message( owner_hwnd, vertical ? WM_VSCROLL : WM_HSCROLL,
                              MAKEWPARAM( SB_THUMBTRACK,
g_tracking_info.thumb_val ),
                              (LPARAM)ctl_hwnd );
.
.
.

}

Till now I did not find any reason, why it not works if I move the scrollbar
via mouse.
If I move it via arrows or mouse wheel it works.
Do you have an idea where I could search next?