patch 9.2.0259: tabpanel: corrupted display during scrolling causing flicker

Problem:  tabpanel: corrupted tabpanel during scrolling causing flicker
Solution: When the tabpanel is visible, force a line-by-line redraw in
          win_do_lines() similarly to popup handling (Yasuhiro Matsumoto).

When a vertical tabpanel is visible, terminal scroll operations in
win_do_lines() affect the full screen width, corrupting the tabpanel
area. The tabpanel is then redrawn via redraw_tabpanel, causing visible
flicker. Return FAIL to force line-by-line redraw instead, analogous to
the existing popup_visible check.

closes: #19832

Signed-off-by: Yasuhiro Matsumoto <[email protected]>
Signed-off-by: Christian Brabandt <[email protected]>

Author: mattn

src/screen.c

@@ -3845,6 +3845,13 @@ win_do_lines(
     if (!no_win_do_lines_ins)
 	clear_cmdline = TRUE;
 
+#if defined(FEAT_TABPANEL)
+    // Terminal scroll operations affect the full screen width, which would
+    // corrupt the vertical tabpanel area and cause flicker.
+    if (tabpanel_width() > 0)
+	return FAIL;
+#endif
+
     /*
      * If the terminal can set a scroll region, use that.
      * Always do this in a vertically split window.  This will redraw from

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    259,
 /**/
     258,
 /**/