Fix horizontal scroll bar dragging in R2L paragraphs.

 src/w32term.c (w32_horizontal_scroll_bar_handle_click): Fix the
 second coordinate ('y') reported for dragging the horizontal
 scroll bar thumb.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/w32term.c b/src/w32term.c
index 4eff5ab4cdd..2772dee6c02 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -4310,7 +4310,10 @@ w32_horizontal_scroll_bar_handle_click (struct scroll_bar *bar, W32Msg *msg,
       case SB_THUMBTRACK:
       case SB_THUMBPOSITION:
         if (HORIZONTAL_SCROLL_BAR_LEFT_RANGE (f, bar->width) <= 0xffff)
-          x = HIWORD (msg->msg.wParam);
+          {
+            x = HIWORD (msg->msg.wParam);
+            y = si.nMax - x - si.nPage;
+          }
         bar->dragging = 1;
         emacs_event->part = scroll_bar_horizontal_handle;