patch 9.1.1856: cannot style popup window (border, shadow, etc)

Problem:  cannot style popup window (border, shadow, etc)
Solution: Extend the 'completepopup' option with additional properties
          (Girish Palya)

This patch extends the 'completepopup' option with additional settings
to allow more configuration of info popup window.

New values:
```
- close           "on" (default) or "off"
- resize          "on" (default) or "off"
- borderchars     specify eight characters (separated by semicolons) to
                  draw the popup border: top, right, bottom, left,
                  topleft, topright, botright, botleft.
- borderhighlight highlight group for the popup border characters
- shadow          pum shadow
```

closes: #18487

Signed-off-by: Girish Palya <girishji@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/insert.txt

@@ -1,4 +1,4 @@
-*insert.txt*    For Vim version 9.1.  Last change: 2025 Oct 12
+*insert.txt*    For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1287,26 +1287,9 @@ remove existing text in the preview window.  The size of the preview window is
 three lines, but 'previewheight' is used when it has a value of 1 or 2.
 
 						*complete-popup*
-When "popup" is in 'completeopt' a popup window is used to display the "info".
+When "popup" is included in 'completeopt', a popup window is used to display
-Then the 'completepopup' option specifies the properties of the popup.  This
+the completion "info" text.  The appearance and behavior of this popup are
-is used when the info popup is created.  The option is a comma-separated list
+controlled by the 'completepopup' option when the popup is created.
-of values:
-	height		maximum height of the popup
-	width		maximum width of the popup
-	highlight	highlight group of the popup (default is PmenuSel)
-	align		"item" (default) or "menu"
-	border		"on" (default) or "off"
-Example: >
-	:set completepopup=height:10,width:60,highlight:InfoPopup
-
-When `"align"` is set to `"item"`, the popup is positioned near the selected
-item, and moves as the selection changes.
-When set to `"menu"`, the popup aligns with the top of the menu (if the menu
-appears below the text), or with the bottom (if the menu appears above).
-
-If the 'mouse' is enabled, a close button and resize handle will appear on the
-popup border.
-
 After creation, the info popup can be located with |popup_findinfo()| and
 modified using |popup_setoptions()|.
 

runtime/doc/options.txt

@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.1.  Last change: 2025 Oct 12
+*options.txt*	For Vim version 9.1.  Last change: 2025 Oct 14
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -2339,12 +2339,50 @@ A jump table for the options with a short description can be found at |Q_op|.
 			global
 			{not available when compiled without the |+textprop|
 			or |+quickfix| feature}
-	When 'completeopt' contains "popup" then this option is used for the
+	When 'completeopt' contains "popup", this option specifies the
 	properties of the info popup when it is created.  If an info popup
 	window already exists it is closed, so that the option value is
 	applied when it is created again.
-	You can also use |popup_findinfo()| and then set properties for an
+
-	existing info popup with |popup_setoptions()|.  See |complete-popup|.
+	The option is a comma-separated list of values:
+		align		"item" (default) or "menu"
+		border		border style:
+				"single"	thin box-drawing characters
+				"double"	double-line
+				"round"		rounded corners
+				"ascii"		ASCII characters (-, |, +)
+				"custom:X;X;X;X;X;X;X;X"
+						eight characters separated by
+						semicolons, in the order: top,
+						right, bottom, left, topleft,
+						topright, botright, botleft
+				"on"		same as "double" when
+						'encoding' is "utf-8" and
+						'ambiwidth' is "single", else
+						"ascii" (default)
+				"off"		no border
+		borderhighlight	highlight group for the popup border characters
+		close		show close button: "on" (default) or "off"
+		height		maximum height of the popup
+		highlight	popup highlight group (default: PmenuSel)
+		resize		show resize handle: "on" (default) or "off"
+		shadow		"off" (default) or "on" using |hl-PmenuShadow|
+		width		maximum width of the popup
+
+	Example: >
+		:set completepopup=height:10,border:single,highlight:InfoPopup
+		:set completepopup=width:60,border:custom:─;│;─;│;┌;┐;┘;└
+<
+	When "align" is set to "item", the popup is positioned near the
+	selected item and moves as the selection changes.
+	When set to "menu", the popup aligns with the top of the menu (if the
+	menu appears below the text) or with the bottom (if it appears above).
+
+	The close button and resize handle are shown on the popup border only
+	when 'mouse' is enabled.
+
+	After creation, the info popup can be located with |popup_findinfo()|
+	and modified using |popup_setoptions()|.  See also: |complete-popup|.
 
 						*'completeslash'* *'csl'*
 'completeslash' 'csl'	string	(default: "")

runtime/doc/version9.txt

@@ -41717,6 +41717,7 @@ Options: ~
   to ">" by default, indicating text that extends beyond the window width.
 - 'guioptions': New value |'go-C'| to style the title/caption bar on Windows 11
   (see also the below platform specific change).
+- 'completepopup': Add more values to style popup windows.
 
 Ex commands: ~
 - allow to specify a priority when defining a new sign |:sign-define|

src/optiondefs.h

@@ -711,7 +711,7 @@ static struct vimoption options[] =
 			    SCTX_INIT},
     {"completepopup", "cpp", P_STRING|P_VI_DEF|P_COMMA|P_NODUP|P_COLON,
 #if defined(FEAT_PROP_POPUP) && defined(FEAT_QUICKFIX)
-			    (char_u *)&p_cpp, PV_NONE, did_set_completepopup, expand_set_popupoption,
+			    (char_u *)&p_cpp, PV_NONE, did_set_completepopup, expand_set_completepopup,
 			    {(char_u *)"", (char_u *)0L}
 #else
 			    (char_u *)NULL, PV_NONE, NULL, NULL,
@@ -1991,7 +1991,7 @@ static struct vimoption options[] =
 			    {(char_u *)12L, (char_u *)0L} SCTX_INIT},
     {"previewpopup", "pvp", P_STRING|P_VI_DEF|P_COMMA|P_NODUP|P_COLON,
 #ifdef FEAT_PROP_POPUP
-			    (char_u *)&p_pvp, PV_NONE, did_set_previewpopup, expand_set_popupoption,
+			    (char_u *)&p_pvp, PV_NONE, did_set_previewpopup, expand_set_previewpopup,
 			    {(char_u *)"", (char_u *)0L}
 #else
 			    (char_u *)NULL, PV_NONE, NULL, NULL,

src/optionstr.c

@@ -70,9 +70,14 @@ static char *(p_fdo_values[]) = {"all", "block", "hor", "mark", "percent",
 static char *(p_kpc_protocol_values[]) = {"none", "mok2", "kitty", NULL};
 #ifdef FEAT_PROP_POPUP
 // Note: Keep this in sync with parse_popup_option()
-static char *(p_popup_option_values[]) = { "align:", "border:", "height:",
+static char *(p_popup_cpp_option_values[]) = {"align:", "border:",
-    "highlight:", "shadow:", "width:", NULL};
+    "borderhighlight:", "close:", "height:", "highlight:", "resize:",
-static char *(p_popup_option_border_values[]) = {"on", "off", NULL};
+    "shadow:", "width:", NULL};
+static char *(p_popup_pvp_option_values[]) = {"height:", "highlight:",
+    "width:", NULL};
+static char *(p_popup_option_on_off_values[]) = {"on", "off", NULL};
+static char *(p_popup_cpp_border_values[]) = {"single", "double", "round",
+    "ascii", "on", "off", "custom:", NULL};
 static char *(p_popup_option_align_values[]) = {"item", "menu", NULL};
 #endif
 #if defined(FEAT_SPELL)
@@ -3408,8 +3413,9 @@ did_set_previewpopup(optset_T *args UNUSED)
     return NULL;
 }
 
-    int
+    static int
-expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches)
+expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches,
+	int previewpopup)
 {
     expand_T *xp = args->oe_xp;
 
@@ -3417,13 +3423,34 @@ expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches)
     {
 	// Within "highlight:"/"border:"/"align:", we have a subgroup of possible options.
 	int border_len = (int)STRLEN("border:");
-	if (xp->xp_pattern - args->oe_set_arg >= border_len &&
+	int close_len = (int)STRLEN("close:");
-		STRNCMP(xp->xp_pattern - border_len, "border:", border_len) == 0)
+	int resize_len = (int)STRLEN("resize:");
+	int shadow_len = (int)STRLEN("shadow:");
+	int is_border = xp->xp_pattern - args->oe_set_arg >= border_len &&
+		STRNCMP(xp->xp_pattern - border_len, "border:", border_len) == 0;
+	int is_close = xp->xp_pattern - args->oe_set_arg >= close_len &&
+		STRNCMP(xp->xp_pattern - close_len, "close:", close) == 0;
+	int is_resize = xp->xp_pattern - args->oe_set_arg >= resize_len &&
+		STRNCMP(xp->xp_pattern - resize_len, "resize:", resize_len) == 0;
+	int is_shadow = xp->xp_pattern - args->oe_set_arg >= shadow_len &&
+		STRNCMP(xp->xp_pattern - shadow_len, "shadow:", shadow_len) == 0;
+	if (is_close || is_resize || is_shadow)
 	{
 	    return expand_set_opt_string(
 		    args,
-		    p_popup_option_border_values,
+		    p_popup_option_on_off_values,
-		    ARRAY_LENGTH(p_popup_option_border_values) - 1,
+		    ARRAY_LENGTH(p_popup_option_on_off_values) - 1,
+		    numMatches,
+		    matches);
+	}
+	if (is_border)
+	{
+	    return expand_set_opt_string(
+		    args,
+		    previewpopup ? p_popup_option_on_off_values
+			: p_popup_cpp_border_values,
+		    (previewpopup ? ARRAY_LENGTH(p_popup_option_on_off_values)
+			: ARRAY_LENGTH(p_popup_cpp_border_values)) - 1,
 		    numMatches,
 		    matches);
 	}
@@ -3439,8 +3466,15 @@ expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches)
 		    matches);
 	}
 	int highlight_len = (int)STRLEN("highlight:");
-	if (xp->xp_pattern - args->oe_set_arg >= highlight_len &&
+	int borderhighlight_len = (int)STRLEN("borderhighlight:");
-		STRNCMP(xp->xp_pattern - highlight_len, "highlight:", highlight_len) == 0)
+	int is_highlight = xp->xp_pattern - args->oe_set_arg >= highlight_len
+	    && STRNCMP(xp->xp_pattern - highlight_len, "highlight:",
+		    highlight_len) == 0;
+	int is_borderhighlight
+	    = xp->xp_pattern - args->oe_set_arg >= borderhighlight_len
+	    && STRNCMP(xp->xp_pattern - borderhighlight_len, "highlight:",
+		    borderhighlight_len) == 0;
+	if (is_highlight || is_borderhighlight)
 	{
 	    // Return the list of all highlight names
 	    return expand_set_opt_generic(
@@ -3454,11 +3488,25 @@ expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches)
 
     return expand_set_opt_string(
 	    args,
-	    p_popup_option_values,
+	    previewpopup ? p_popup_pvp_option_values
-	    ARRAY_LENGTH(p_popup_option_values) - 1,
+		: p_popup_cpp_option_values,
+	    previewpopup ? ARRAY_LENGTH(p_popup_pvp_option_values) - 1
+		: ARRAY_LENGTH(p_popup_cpp_option_values) - 1,
 	    numMatches,
 	    matches);
 }
+
+    int
+expand_set_previewpopup(optexpand_T *args, int *numMatches, char_u ***matches)
+{
+    return expand_set_popupoption(args, numMatches, matches, TRUE);
+}
+
+    int
+expand_set_completepopup(optexpand_T *args, int *numMatches, char_u ***matches)
+{
+    return expand_set_popupoption(args, numMatches, matches, FALSE);
+}
 #endif
 
 #if defined(FEAT_POSTSCRIPT)

src/popupwin.c

@@ -1219,8 +1219,10 @@ popup_adjust_position(win_T *wp)
     int		center_hor = FALSE;
     int		allow_adjust_left = !wp->w_popup_fixed;
     int		top_extra = popup_top_extra(wp);
-    int		right_extra = wp->w_popup_border[1] + wp->w_popup_padding[1];
+    int		right_extra = wp->w_popup_border[1] + wp->w_popup_padding[1]
-    int		bot_extra = wp->w_popup_border[2] + wp->w_popup_padding[2];
+		    + (wp->w_popup_shadow ? 2 : 0);
+    int		bot_extra = wp->w_popup_border[2] + wp->w_popup_padding[2]
+		    + wp->w_popup_shadow;
     int		left_extra = wp->w_popup_border[3] + wp->w_popup_padding[3];
     int		extra_height = top_extra + bot_extra;
     int		extra_width = left_extra + right_extra;
@@ -1782,6 +1784,21 @@ popup_set_buffer_text(buf_T *buf, typval_T text)
     curbuf = curwin->w_buffer;
 }
 
+#define SET_BORDER_CHARS(a0, a1, a2, a3, a4, a5, a6, a7)    \
+    do {						    \
+	if (wp != NULL)					    \
+	{						    \
+	    wp->w_border_char[0] = (a0);		    \
+	    wp->w_border_char[1] = (a1);		    \
+	    wp->w_border_char[2] = (a2);		    \
+	    wp->w_border_char[3] = (a3);		    \
+	    wp->w_border_char[4] = (a4);		    \
+	    wp->w_border_char[5] = (a5);		    \
+	    wp->w_border_char[6] = (a6);		    \
+	    wp->w_border_char[7] = (a7);		    \
+	}						    \
+    } while (0)
+
 /*
  * Parse the 'previewpopup' or 'completepopup' option and apply the values to
  * window "wp" if it is not NULL.
@@ -1795,6 +1812,7 @@ parse_popup_option(win_T *wp, int is_preview)
 	!is_preview ? p_cpp :
 #endif
 	p_pvp;
+    int	    border_enabled = FALSE;
 
     if (wp != NULL)
 	wp->w_popup_flags &= ~POPF_INFO_MENU;
@@ -1847,28 +1865,159 @@ parse_popup_option(win_T *wp, int is_preview)
 
 		*p = NUL;
 		set_string_option_direct_in_win(wp, (char_u *)"wincolor", -1,
-						s + 10, OPT_FREE|OPT_LOCAL, 0);
+			s + 10, OPT_FREE|OPT_LOCAL, 0);
 		*p = c;
 	    }
 	}
+	else if (STRNCMP(s, "borderhighlight:", 16) == 0)
+	{
+	    char_u	*arg = s + 16;
+
+	    if (*arg == NUL || *arg == ',')
+		return FAIL;
+	    if (wp != NULL)
+	    {
+		for (int i = 0; i < 4; ++i)
+		{
+		    VIM_CLEAR(wp->w_border_highlight[i]);
+		    wp->w_border_highlight[i] = vim_strnsave(arg, p - arg);
+		}
+	    }
+	}
 	else if (STRNCMP(s, "border:", 7) == 0)
 	{
-	    // Note: Keep this in sync with p_popup_option_border_values.
 	    char_u	*arg = s + 7;
-	    int		on = STRNCMP(arg, "on", 2) == 0 && arg + 2 == p;
-	    int		off = STRNCMP(arg, "off", 3) == 0 && arg + 3 == p;
 	    int		i;
+	    int		token_len = p - arg;
+	    char_u	*token;
+	    // Use box-drawing characters only when 'encoding' is "utf-8" and
+	    // 'ambiwidth' is "single".
+	    int		can_use_box_chars = (enc_utf8 && *p_ambw == 's');
 
-	    if (!on && !off)
+	    if (token_len == 0
+			|| (STRNCMP(arg, "off", 3) == 0 && arg + 3 == p))
+	    {
+		if (wp != NULL)
+		{
+		    for (i = 0; i < 4; ++i)
+			wp->w_popup_border[i] = 0;
+		    SET_BORDER_CHARS(0, 0, 0, 0, 0, 0, 0, 0);
+		    // only show the X for close when there is a border
+		    wp->w_popup_close = POPCLOSE_NONE;
+		}
+		continue;
+	    }
+
+	    token = vim_strnsave(arg, token_len);
+	    if (token == NULL)
 		return FAIL;
+
+	    if ((can_use_box_chars && (STRCMP(token, "single") == 0
+			    || STRCMP(token, "double") == 0
+			    || STRCMP(token, "on") == 0
+			    || STRCMP(token, "round") == 0))
+		    || STRCMP(token, "ascii") == 0
+		    || (STRNCMP(token, "custom:", 7) == 0))
+	    {
+		if (STRCMP(token, "single") == 0)
+		    SET_BORDER_CHARS(0x2500, 0x2502, 0x2500, 0x2502, // ─ │ ─ │
+			    0x250c, 0x2510, 0x2518, 0x2514); // ┌ ┐ ┘ └
+		else if (STRCMP(token, "double") == 0)
+		    SET_BORDER_CHARS(0x2550, 0x2551, 0x2550, 0x2551, // ═ ║ ═ ║
+			    0x2554, 0x2557, 0x255D, 0x255A); // ╔ ╗ ╝  ╚
+		else if (STRCMP(token, "round") == 0)
+		    SET_BORDER_CHARS(0x2500, 0x2502, 0x2500, 0x2502, // ─ │ ─ │
+			    0x256d, 0x256e, 0x256f, 0x2570); // ╭ ╮ ╯ ╰
+		else if (STRCMP(token, "on") == 0)
+		    SET_BORDER_CHARS(0, 0, 0, 0, 0, 0, 0, 0);
+		else if (STRCMP(token, "ascii") == 0)
+		    SET_BORDER_CHARS('-', '|', '-', '|', '+', '+', '+', '+');
+		else if (STRNCMP(token, "custom:", 7) == 0)
+		{
+		    char_u	*q = token + 7;
+		    int		out[8];
+		    int		failed = FALSE;
+
+		    SET_BORDER_CHARS(0, 0, 0, 0, 0, 0, 0, 0);
+
+		    for (i = 0; i < 8 && !failed; i++)
+		    {
+			if (*q == NUL)
+			    failed = TRUE;
+			else
+			{
+			    out[i] = mb_ptr2char(q);
+			    mb_ptr2char_adv(&q);
+			    if (i < 7)
+			    {
+				if (*q != ';')
+				    failed = TRUE; // must be semicolon
+				q++;
+			    }
+			}
+		    }
+		    if (failed || *q != NUL) // must end exactly after the 8th char
+		    {
+			vim_free(token);
+			return FAIL;
+		    }
+		    SET_BORDER_CHARS(out[0], out[1], out[2], out[3], out[4],
+			    out[5], out[6], out[7]);
+		}
+	    }
+	    else
+	    {
+		vim_free(token);
+		return FAIL;
+	    }
+
 	    if (wp != NULL)
 	    {
 		for (i = 0; i < 4; ++i)
-		    wp->w_popup_border[i] = on ? 1 : 0;
+		    wp->w_popup_border[i] = 1;
-		if (off)
-		    // only show the X for close when there is a border
-		    wp->w_popup_close = POPCLOSE_NONE;
 	    }
+	    border_enabled = TRUE;
+
+	    vim_free(token);
+	}
+	else if (STRNCMP(s, "close:", 6) == 0)
+	{
+	    char_u	*arg = s + 6;
+	    int		on = STRNCMP(arg, "on", 2) == 0 && arg + 2 == p;
+	    int		off = STRNCMP(arg, "off", 3) == 0 && arg + 3 == p;
+
+	    if ((!on && !off) || is_preview)
+		return FAIL;
+	    on = on && mouse_has(MOUSE_INSERT) && border_enabled;
+	    if (wp != NULL)
+		wp->w_popup_close = on ? POPCLOSE_BUTTON : POPCLOSE_NONE;
+	}
+	else if (STRNCMP(s, "resize:", 7) == 0)
+	{
+	    char_u	*arg = s + 7;
+	    int		on = STRNCMP(arg, "on", 2) == 0 && arg + 2 == p;
+	    int		off = STRNCMP(arg, "off", 3) == 0 && arg + 3 == p;
+
+	    if ((!on && !off) || is_preview)
+		return FAIL;
+	    if (wp != NULL)
+	    {
+		if (on && mouse_has(MOUSE_INSERT))
+		    wp->w_popup_flags |= POPF_RESIZE;
+		else
+		    wp->w_popup_flags &= ~POPF_RESIZE;
+	    }
+	}
+	else if (STRNCMP(s, "shadow:", 7) == 0)
+	{
+	    char_u	*arg = s + 7;
+	    int		on = STRNCMP(arg, "on", 2) == 0 && arg + 2 == p;
+	    int		off = STRNCMP(arg, "off", 3) == 0 && arg + 3 == p;
+
+	    if ((!on && !off) || is_preview)
+		return FAIL;
+	    if (wp != NULL)
+		wp->w_popup_shadow = on ? 1 : 0;
 	}
 	else if (STRNCMP(s, "align:", 6) == 0)
 	{
@@ -2297,6 +2446,12 @@ popup_create(typval_T *argvars, typval_T *rettv, create_type_T type)
 	parse_previewpopup(wp);
 	popup_set_wantpos_cursor(wp, wp->w_minwidth, d);
     }
+
+    for (i = 0; i < 4; ++i)
+	VIM_CLEAR(wp->w_border_highlight[i]);
+    for (i = 0; i < 8; ++i)
+	wp->w_border_char[i] = 0;
+
 # ifdef FEAT_QUICKFIX
     if (type == TYPE_INFO)
     {
@@ -2311,10 +2466,6 @@ popup_create(typval_T *argvars, typval_T *rettv, create_type_T type)
     }
 # endif
 
-    for (i = 0; i < 4; ++i)
-	VIM_CLEAR(wp->w_border_highlight[i]);
-    for (i = 0; i < 8; ++i)
-	wp->w_border_char[i] = 0;
     wp->w_want_scrollbar = 1;
     wp->w_popup_fixed = 0;
     wp->w_filter_mode = MODE_ALL;
@@ -4151,7 +4302,6 @@ update_popups(void (*win_update)(win_T *wp))
 	else
 	    wp->w_popup_flags &= ~POPF_ON_CMDLINE;
 
-
 	// We can only use these line drawing characters when 'encoding' is
 	// "utf-8" and 'ambiwidth' is "single".
 	if (enc_utf8 && *p_ambw == 's')
@@ -4374,6 +4524,18 @@ update_popups(void (*win_update)(win_T *wp))
 			popup_attr);
 	}
 
+	// right shadow
+	if (wp->w_popup_shadow)
+	{
+	    int col = wincol + total_width;
+	    for (i = 0; i < total_height; ++i)
+	    {
+		row = wp->w_winrow + i + 1;
+		put_shadow_char(row, col);
+		put_shadow_char(row, col + 1);
+	    }
+	}
+
 	if (wp->w_popup_padding[2] > 0)
 	{
 	    // bottom padding
@@ -4387,7 +4549,7 @@ update_popups(void (*win_update)(win_T *wp))
 	{
 	    // bottom border
 	    row = wp->w_winrow + total_height - 1;
-	    screen_fill(row , row + 1,
+	    screen_fill(row, row + 1,
 		    wincol < 0 ? 0 : wincol,
 		    wincol + total_width,
 		    wp->w_popup_border[3] != 0 && wp->w_popup_leftoff == 0
@@ -4400,6 +4562,15 @@ update_popups(void (*win_update)(win_T *wp))
 	    }
 	}
 
+	if (wp->w_popup_shadow)
+	{
+	    // bottom shadow
+	    row = wp->w_winrow + total_height;
+	    for (int col = 2 + (wincol < 0 ? 0 : wincol);
+		    col < wincol + total_width; col++)
+		put_shadow_char(row, col);
+	}
+
 	if (wp->w_popup_close == POPCLOSE_BUTTON)
 	{
 	    // close button goes on top of anything at the top-right corner

src/proto/optionstr.pro

@@ -130,7 +130,8 @@ int expand_set_nrformats(optexpand_T *args, int *numMatches, char_u ***matches);
 char *did_set_optexpr(optset_T *args);
 char *did_set_pastetoggle(optset_T *args);
 char *did_set_previewpopup(optset_T *args);
-int expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches);
+int expand_set_previewpopup(optexpand_T *args, int *numMatches, char_u ***matches);
+int expand_set_completepopup(optexpand_T *args, int *numMatches, char_u ***matches);
 char *did_set_printencoding(optset_T *args);
 int expand_set_printoptions(optexpand_T *args, int *numMatches, char_u ***matches);
 char *did_set_renderoptions(optset_T *args);

src/structs.h

@@ -4054,6 +4054,7 @@ struct window_S
     int		w_popup_border[4];  // popup border top/right/bot/left
     char_u	*w_border_highlight[4];  // popup border highlight
     int		w_border_char[8];   // popup border characters
+    int		w_popup_shadow;     // popup shadow (right and bottom edges)
 
     int		w_popup_leftoff;    // columns left of the screen
     int		w_popup_rightoff;   // columns right of the screen

src/testdir/dumps/Test_popupwin_infopopup_9.dump

@@ -0,0 +1,14 @@
+|a+0&#ffffff0|w|o|r|d| @69
+|a|w|o|r|d> @69
+|w+0#0000001#e0e0e08|r|d| @4|W| |e|x|t|r|a| |t|e|x|t| | +0#0000000#0000001| +0#0000001#e0e0e08|w|o|r|d|s| |a|r|e| |c|o@1|l| | +0#4040ff13#ffffff0@36
+|a+0#0000001#ffd7ff255|n|o|t|w|r|d| |W| |e|x|t|r|a| |t|e|x|t| | +0#0000000#0000001| +0#4040ff13#ffffff0@1| +0#6c6c6c255#0000001@15| +0#4040ff13#ffffff0@34
+|n+0#0000001#ffd7ff255|o|a|w|r|d| @1|W| |e|x|t|r|a| |t|e|x|t| | +0#0000000#a8a8a8255| +0#4040ff13#ffffff0@52
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|-+2#0000000&@1| |U|s|e|r| |d|e|f|i|n|e|d| |c|o|m|p|l|e|t|i|o|n| |(|^|U|^|N|^|P|)| |m+0#00e0003&|a|t|c|h| |1| |o|f| |4| +0#0000000&@26

src/testdir/test_options.vim

@@ -637,7 +637,7 @@ func Test_set_completion_string_values()
   set keyprotocol&
 
   " previewpopup / completepopup
-  call assert_equal('align:', getcompletion('set previewpopup=', 'cmdline')[0])
+  call assert_equal('height:', getcompletion('set previewpopup=', 'cmdline')[0])
   call assert_equal('EndOfBuffer', getcompletion('set previewpopup=highlight:End*Buffer', 'cmdline')[0])
   call feedkeys(":set previewpopup+=border:\<Tab>\<C-B>\"\<CR>", 'xt')
   call assert_equal('"set previewpopup+=border:on', @:)

src/testdir/test_popupwin.vim

@@ -3701,6 +3701,12 @@ func Test_popupmenu_info_border()
   call term_sendkeys(buf, "a\<C-X>\<C-U>")
   call VerifyScreenDump(buf, 'Test_popupwin_infopopup_8', {})
 
+  " Test shadow
+  call term_sendkeys(buf, "\<Esc>")
+  call term_sendkeys(buf, ":set completepopup=border:off,shadow:on\<CR>")
+  call term_sendkeys(buf, "Sa\<C-X>\<C-U>")
+  call VerifyScreenDump(buf, 'Test_popupwin_infopopup_9', {})
+
   call term_sendkeys(buf, "\<Esc>")
   call StopVimInTerminal(buf)
 endfunc

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1856,
 /**/
     1855,
 /**/