patch 9.2.0239: signcolumn may cause flicker

Problem:  Changing the 'signcolumn' may cause flicker, because it uses
          the P_RCLR flag for redrawing (Yggdroot)
Solution: Change 'signcolumn' to use P_RWIN instead of P_RCLR, matching
          the behavior of 'number' and 'foldcolumn'
          (Yasuhiro Matsumoto).

fixes:  #19663
closes: #19713

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: mattn

src/optiondefs.h

@@ -2416,7 +2416,7 @@ static struct vimoption options[] =
     {"sidescrolloff", "siso", P_NUM|P_VI_DEF|P_VIM|P_RBUF,
 			    (char_u *)&p_siso, PV_SISO, NULL, NULL,
 			    {(char_u *)0L, (char_u *)0L} SCTX_INIT},
-    {"signcolumn",   "scl",  P_STRING|P_ALLOCED|P_VI_DEF|P_RCLR,
+    {"signcolumn",   "scl",  P_STRING|P_ALLOCED|P_VI_DEF|P_RWIN,
 #ifdef FEAT_SIGNS
 			    (char_u *)VAR_WIN, PV_SCL, did_set_signcolumn, expand_set_signcolumn,
 			    {(char_u *)"auto", (char_u *)0L}

src/optionstr.c

@@ -4080,6 +4080,13 @@ did_set_signcolumn(optset_T *args)
 	curwin->w_nrwidth_line_count = 0;
 # endif
 
+# if defined(FEAT_GUI)
+    // In the GUI, when sign icons are used, a full screen clear is needed
+    // to properly redraw the sign icons.
+    if (gui.in_use && curbuf->b_signlist != NULL)
+	redraw_all_later(UPD_CLEAR);
+# endif
+
     return NULL;
 }