func (sv *ScrollView) updateScrollBars() {
s := sv.composite.Size()
clb := sv.ClientBounds()
var si win.SCROLLINFO
si.CbSize = uint32(unsafe.Sizeof(si))
si.FMask = win.SIF_PAGE | win.SIF_RANGE
si.NMax = int32(s.Width - 1)
si.NPage = uint32(clb.Width)
win.SetScrollInfo(sv.hWnd, win.SB_HORZ, &si, false)
sv.composite.SetX(sv.scroll(win.SB_HORZ, win.SB_THUMBPOSITION))
si.NMax = int32(s.Height - 1)
si.NPage = uint32(clb.Height)
win.SetScrollInfo(sv.hWnd, win.SB_VERT, &si, false)
sv.composite.SetY(sv.scroll(win.SB_VERT, win.SB_THUMBPOSITION))
}
