patch 9.1.1430: tabpanel may flicker in the GUI

Problem:  tabpanel may flicker in the GUI
Solution: call scroll_start() and scroll_region_reset()
          (Hirohito Higashi)

fixes: #17440
closes: #17442

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/term.c b/src/term.c
index b7a82da..649e483 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4478,7 +4478,9 @@
 {
     OUT_STR(tgoto((char *)T_CS, (int)Rows - 1, 0));
     if (*T_CSV != NUL)
-	OUT_STR(tgoto((char *)T_CSV, Columns - 1, 0));
+	OUT_STR(tgoto((char *)T_CSV,
+		    firstwin->w_wincol + topframe->fr_width - 1,
+		    firstwin->w_wincol));
     screen_start();		    // don't know where cursor is now
 }