patch 9.2.0080: popup: a few redrawing problems

Problem:   Popup windows leave ghost images when moved. Visual options
           do not trigger a redraw when updated via popup_setoptions().
           An empty borderhighlight list fails to clear existing
           highlights.
Solution:  Modify f_popup_move() in src/popupwin.c to save the old
           position before moving and force a redraw. Enhance
           f_popup_setoptions() to trigger a redraw when
           visual-affecting options change. Modify
           apply_general_options() to explicitly clear border
           highlights when an empty list is provided
           (Yasuhiro Matsumoto).

closes: #19297

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

src/drawscreen.c

@@ -97,6 +97,9 @@ update_screen(int type_arg)
 #endif
     int		no_update = FALSE;
     int		save_pum_will_redraw = pum_will_redraw;
+#ifdef FEAT_PROP_POPUP
+    int		did_redraw_window = FALSE;
+#endif
 
     // Don't do anything if the screen structures are (not yet) valid.
     if (!screen_valid(TRUE))
@@ -319,6 +322,9 @@ update_screen(int type_arg)
 	if (wp->w_redr_type != 0)
 	{
 	    cursor_off();
+#ifdef FEAT_PROP_POPUP
+	    did_redraw_window = TRUE;
+#endif
 #ifdef FEAT_GUI
 	    if (!did_one)
 	    {
@@ -363,7 +369,8 @@ update_screen(int type_arg)
 
 #ifdef FEAT_PROP_POPUP
     // Display popup windows on top of the windows and command line.
-    update_popups(win_update);
+    if (did_redraw_window || popup_need_redraw())
+	update_popups(win_update);
 #endif
 
 #ifdef FEAT_TERMINAL

src/highlight.c

@@ -3167,14 +3167,15 @@ hl_blend_attr(int char_attr, int popup_attr, int blend, int blend_fg UNUSED)
 	    {
 		if (blend_fg)
 		{
-		    // blend_fg=TRUE: blend bg text fg from popup bg color to white
+		    // blend_fg=TRUE: fade underlying text toward popup bg.
-		    // At blend=0: fg becomes popup bg (blue, invisible - opaque popup)
-		    // At blend=100: fg is white (visible - transparent popup)
-		    // Always use white (0xFFFFFF) as the target color for consistency
 		    if (popup_aep->ae_u.gui.bg_color != INVALCOLOR)
 		    {
+			int base_fg = 0xFFFFFF;
+			if (char_aep != NULL
+				&& char_aep->ae_u.gui.fg_color != INVALCOLOR)
+			    base_fg = char_aep->ae_u.gui.fg_color;
 			new_en.ae_u.gui.fg_color = blend_colors(
-				popup_aep->ae_u.gui.bg_color, 0xFFFFFF, blend);
+				base_fg, popup_aep->ae_u.gui.bg_color, blend);
 		    }
 		}
 		else if (popup_aep->ae_u.gui.fg_color != INVALCOLOR)
@@ -3230,12 +3231,15 @@ hl_blend_attr(int char_attr, int popup_attr, int blend, int blend_fg UNUSED)
 		// Blend RGB colors for termguicolors mode
 		if (blend_fg)
 		{
-		    // blend_fg=TRUE: blend bg text fg from popup bg color to white
+		    // blend_fg=TRUE: fade underlying text toward popup bg.
-		    // Always use white (0xFFFFFF) as the target color for consistency
 		    if (popup_aep->ae_u.cterm.bg_rgb != INVALCOLOR)
 		    {
+			int base_fg = 0xFFFFFF;
+			if (char_aep != NULL
+				&& char_aep->ae_u.cterm.fg_rgb != INVALCOLOR)
+			    base_fg = char_aep->ae_u.cterm.fg_rgb;
 			new_en.ae_u.cterm.fg_rgb = blend_colors(
-				popup_aep->ae_u.cterm.bg_rgb, 0xFFFFFF, blend);
+				base_fg, popup_aep->ae_u.cterm.bg_rgb, blend);
 		    }
 		}
 		else if (popup_aep->ae_u.cterm.fg_rgb != INVALCOLOR)

src/popupwin.c

@@ -852,23 +852,36 @@ apply_general_options(win_T *wp, dict_T *dict)
 	    int		i;
 
 	    CHECK_LIST_MATERIALIZE(list);
-	    for (i = 0, li = list->lv_first; i < 4 && i < list->lv_len;
+	    wp->w_border_highlight_isset = TRUE;
-						     ++i, li = li->li_next)
+	    // Clear all highlights if list is empty
+	    if (list->lv_len == 0)
 	    {
-		str = tv_get_string(&li->li_tv);
+		for (i = 0; i < 4; ++i)
-		if (*str != NUL)
 		{
 		    vim_free(wp->w_border_highlight[i]);
-		    wp->w_border_highlight[i] = vim_strsave(str);
+		    wp->w_border_highlight[i] = NULL;
 		}
 	    }
-	    if (list->lv_len == 1 && wp->w_border_highlight[0] != NULL)
+	    else
-		for (i = 1; i < 4; ++i)
+	    {
+		for (i = 0, li = list->lv_first; i < 4 && i < list->lv_len;
+						     ++i, li = li->li_next)
 		{
-		    vim_free(wp->w_border_highlight[i]);
+		    str = tv_get_string(&li->li_tv);
-		    wp->w_border_highlight[i] =
+		    if (*str != NUL)
-					vim_strsave(wp->w_border_highlight[0]);
+		    {
+			vim_free(wp->w_border_highlight[i]);
+			wp->w_border_highlight[i] = vim_strsave(str);
+		    }
 		}
+		if (list->lv_len == 1 && wp->w_border_highlight[0] != NULL)
+		    for (i = 1; i < 4; ++i)
+		    {
+			vim_free(wp->w_border_highlight[i]);
+			wp->w_border_highlight[i] =
+					vim_strsave(wp->w_border_highlight[0]);
+		    }
+	    }
 	}
     }
 
@@ -2180,6 +2193,23 @@ popup_redraw_all(void)
 	wp->w_redr_type = UPD_NOT_VALID;
 }
 
+/*
+ * Return TRUE if any visible popup window needs a redraw.
+ */
+    int
+popup_need_redraw(void)
+{
+    win_T	*wp;
+
+    FOR_ALL_POPUPWINS(wp)
+	if ((wp->w_popup_flags & POPF_HIDDEN) == 0 && wp->w_redr_type != 0)
+	    return TRUE;
+    FOR_ALL_POPUPWINS_IN_TAB(curtab, wp)
+	if ((wp->w_popup_flags & POPF_HIDDEN) == 0 && wp->w_redr_type != 0)
+	    return TRUE;
+    return FALSE;
+}
+
 /*
  * Set the color for a notification window.
  */
@@ -3238,6 +3268,10 @@ f_popup_move(typval_T *argvars, typval_T *rettv UNUSED)
     dict_T	*dict;
     int		id;
     win_T	*wp;
+    int		old_winrow;
+    int		old_wincol;
+    int		old_height;
+    int		old_width;
 
     if (in_vim9script()
 	    && (check_for_number_arg(argvars, 0) == FAIL
@@ -3253,11 +3287,22 @@ f_popup_move(typval_T *argvars, typval_T *rettv UNUSED)
 	return;
     dict = argvars[1].vval.v_dict;
 
+    // Save old position for redrawing
+    old_winrow = wp->w_winrow;
+    old_wincol = wp->w_wincol;
+    old_height = wp->w_height;
+    old_width = wp->w_width;
+
     apply_move_options(wp, dict);
 
     if (wp->w_winrow + wp->w_height >= cmdline_row)
 	clear_cmdline = TRUE;
     popup_adjust_position(wp);
+
+    // Redraw the old position to clear ghost images
+    if (old_winrow != wp->w_winrow || old_wincol != wp->w_wincol
+	    || old_height != wp->w_height || old_width != wp->w_width)
+	redraw_all_later(UPD_NOT_VALID);
 }
 
 /*
@@ -3273,6 +3318,13 @@ f_popup_setoptions(typval_T *argvars, typval_T *rettv UNUSED)
 #ifdef FEAT_PROP_POPUP
     int		old_blend;
 #endif
+    int		old_zindex;
+    int		old_popup_flags;
+    char_u	*old_scrollbar_highlight;
+    char_u	*old_thumb_highlight;
+    char_u	*old_border_highlight[4];
+    int		need_redraw = FALSE;
+    int		i;
 
     if (in_vim9script()
 	    && (check_for_number_arg(argvars, 0) == FAIL
@@ -3291,10 +3343,34 @@ f_popup_setoptions(typval_T *argvars, typval_T *rettv UNUSED)
 #ifdef FEAT_PROP_POPUP
     old_blend = wp->w_popup_blend;
 #endif
+    old_zindex = wp->w_zindex;
+    old_popup_flags = wp->w_popup_flags;
+    old_scrollbar_highlight = wp->w_scrollbar_highlight;
+    old_thumb_highlight = wp->w_thumb_highlight;
+    for (i = 0; i < 4; i++)
+	old_border_highlight[i] = wp->w_border_highlight[i];
 
     (void)apply_options(wp, dict, FALSE);
 
+    // Check if visual options changed and redraw if needed
     if (old_firstline != wp->w_firstline)
+	need_redraw = TRUE;
+    if (old_zindex != wp->w_zindex)
+	need_redraw = TRUE;
+    if (old_popup_flags != wp->w_popup_flags)
+	need_redraw = TRUE;
+    if (old_scrollbar_highlight != wp->w_scrollbar_highlight)
+	need_redraw = TRUE;
+    if (old_thumb_highlight != wp->w_thumb_highlight)
+	need_redraw = TRUE;
+    for (i = 0; i < 4; i++)
+	if (old_border_highlight[i] != wp->w_border_highlight[i])
+	{
+	    need_redraw = TRUE;
+	    break;
+	}
+
+    if (need_redraw)
 	redraw_win_later(wp, UPD_NOT_VALID);
 #ifdef FEAT_PROP_POPUP
     // Force redraw if opacity value changed
@@ -3432,7 +3508,9 @@ get_borderhighlight(dict_T *dict, win_T *wp)
     for (i = 0; i < 4; ++i)
 	if (wp->w_border_highlight[i] != NULL)
 	    break;
-    if (i == 4)
+    // Only include "borderhighlight" if it was explicitly set (even if empty)
+    // or if at least one highlight is set.
+    if (i == 4 && !wp->w_border_highlight_isset)
 	return;
 
     list = list_alloc();
@@ -3440,6 +3518,9 @@ get_borderhighlight(dict_T *dict, win_T *wp)
 	return;
 
     dict_add_list(dict, "borderhighlight", list);
+    // When all highlights are NULL (cleared to empty list), return empty list.
+    if (i == 4)
+	return;
     for (i = 0; i < 4; ++i)
 	list_append_string(list, wp->w_border_highlight[i], -1);
 }
@@ -4240,11 +4321,68 @@ may_update_popup_position(void)
 	popup_adjust_position(curwin);
 }
 
+#ifdef FEAT_PROP_POPUP
+static schar_T *base_screenlines = NULL;
+static int *base_screenattrs = NULL;
+static u8char_T *base_screenlinesuc = NULL;
+static int base_screen_rows = 0;
+static int base_screen_cols = 0;
+
+/*
+ * Get the base screen cell saved before drawing opacity popups.
+ * Returns TRUE if the cell is available.
+ */
+    int
+popup_get_base_screen_cell(int row, int col, schar_T *linep, int *attrp,
+							  u8char_T *ucp)
+{
+    if (base_screenlines == NULL || base_screenattrs == NULL)
+	return FALSE;
+    if (row < 0 || col < 0 || row >= base_screen_rows
+						     || col >= base_screen_cols)
+	return FALSE;
+
+    int off = row * base_screen_cols + col;
+    if (linep != NULL)
+	*linep = base_screenlines[off];
+    if (attrp != NULL)
+	*attrp = base_screenattrs[off];
+    if (ucp != NULL)
+    {
+	if (enc_utf8 && base_screenlinesuc != NULL)
+	    *ucp = base_screenlinesuc[off];
+	else
+	    *ucp = 0;
+    }
+    return TRUE;
+}
+
+/*
+ * Set the base screen cell saved before drawing opacity popups.
+ * Used to update the snapshot after blending a layer.
+ */
+    void
+popup_set_base_screen_cell(int row, int col, schar_T line, int attr, u8char_T uc)
+{
+    if (base_screenlines == NULL || base_screenattrs == NULL)
+	return;
+    if (row < 0 || col < 0 || row >= base_screen_rows
+						     || col >= base_screen_cols)
+	return;
+
+    int off = row * base_screen_cols + col;
+    base_screenlines[off] = line;
+    base_screenattrs[off] = attr;
+    if (enc_utf8 && base_screenlinesuc != NULL)
+	base_screenlinesuc[off] = uc;
+}
+#endif
+
 /*
  * Draw a single padding cell with opacity blending.
  * Restores background from saved data and blends with popup attribute.
  */
-    static void
+static void
 draw_opacity_padding_cell(
 	int		row,
 	int		col,
@@ -4254,7 +4392,9 @@ draw_opacity_padding_cell(
 	int		save_start_row,
 	int		save_start_col,
 	int		save_rows,
-	int		save_cols)
+	int		save_cols,
+	int		pad_start_col,
+	int		pad_end_col)
 {
     int off = LineOffset[row] + col;
     int r = row - save_start_row;
@@ -4263,14 +4403,165 @@ draw_opacity_padding_cell(
     if (r >= 0 && r < save_rows && c >= 0 && c < save_cols)
     {
 	int save_off = r * save_cols + c;
+	// If this is the second cell of a wide background character, blend
+	// the wide character instead of overwriting it.
+	if (enc_utf8 && saved_screenlinesuc != NULL)
+	{
+	    int base_col = col - 1;
+	    int base_off = off - 1;
+	    int base_save_off = save_off - 1;
+	    int wide_prev = FALSE;
+
+	    // Prefer current screen state for detecting a wide char, since the
+	    // saved data may not contain a reliable right-half marker.
+	    if (base_off >= 0 && ScreenLines != NULL)
+	    {
+		if (ScreenLinesUC != NULL
+			&& ScreenLinesUC[base_off] != 0
+			&& utf_char2cells(ScreenLinesUC[base_off]) == 2
+			&& ScreenLines[off] == 0)
+		    wide_prev = TRUE;
+	    }
+	    if (!wide_prev && save_off > 0)
+	    {
+		if (saved_screenlinesuc[save_off - 1] != 0
+			&& utf_char2cells(saved_screenlinesuc[save_off - 1]) == 2
+			&& saved_screenlines[save_off] == 0)
+		    wide_prev = TRUE;
+	    }
+
+	    if (wide_prev && base_col >= 0)
+	    {
+		// If the wide character starts outside the padding area, do not
+		// overwrite it. Use the base screen cell if available.
+		if (base_col < pad_start_col)
+		{
+		    if (ScreenLinesUC != NULL
+			    && ScreenLinesUC[base_off] != 0
+			    && utf_char2cells(ScreenLinesUC[base_off]) == 2)
+		    {
+			// The left half still has the wide char on screen.
+			// Clear it to a space.
+			ScreenLines[base_off] = ' ';
+			ScreenLinesUC[base_off] = 0;
+			ScreenAttrs[base_off] = saved_screenattrs[base_save_off];
+			screen_char(base_off, row, base_col);
+
+			// Draw padding in the right half.
+			ScreenLines[off] = ' ';
+			ScreenAttrs[off] = saved_screenattrs[save_off];
+			if (enc_utf8)
+			    ScreenLinesUC[off] = 0;
+			int popup_attr_val =
+					get_wcr_attr(screen_opacity_popup);
+			int blend = screen_opacity_popup->w_popup_blend;
+			ScreenAttrs[off] = hl_blend_attr(ScreenAttrs[off],
+					popup_attr_val, blend, TRUE);
+			popup_set_base_screen_cell(row, col,
+				ScreenLines[off], ScreenAttrs[off],
+				ScreenLinesUC[off]);
+			screen_char(off, row, col);
+			return;
+		    }
+
+		    // screen_line() already cleared the base cell (popup
+		    // content was a space).  Restore the full wide char from
+		    // saved background so it shows through with opacity.
+		    if (base_save_off >= 0
+			    && saved_screenlinesuc != NULL
+			    && saved_screenlinesuc[base_save_off] != 0
+			    && utf_char2cells(
+				saved_screenlinesuc[base_save_off]) == 2)
+		    {
+			ScreenLines[base_off] =
+					saved_screenlines[base_save_off];
+			ScreenLinesUC[base_off] =
+					saved_screenlinesuc[base_save_off];
+			ScreenLines[off] = saved_screenlines[save_off];
+			ScreenLinesUC[off] = saved_screenlinesuc[save_off];
+			ScreenAttrs[base_off] =
+					saved_screenattrs[base_save_off];
+			ScreenAttrs[off] = saved_screenattrs[save_off];
+
+			int popup_attr_val =
+					get_wcr_attr(screen_opacity_popup);
+			int blend = screen_opacity_popup->w_popup_blend;
+			ScreenAttrs[base_off] = hl_blend_attr(
+				ScreenAttrs[base_off],
+				popup_attr_val, blend, TRUE);
+			ScreenAttrs[off] = ScreenAttrs[base_off];
+			popup_set_base_screen_cell(row, base_col,
+				ScreenLines[base_off],
+				ScreenAttrs[base_off],
+				ScreenLinesUC[base_off]);
+			popup_set_base_screen_cell(row, col,
+				ScreenLines[off], ScreenAttrs[off],
+				ScreenLinesUC[off]);
+			screen_char(base_off, row, base_col);
+			return;
+		    }
+
+		    // Draw padding in the right half.
+		    ScreenLines[off] = ' ';
+		    ScreenAttrs[off] = saved_screenattrs[save_off];
+		    if (enc_utf8 && ScreenLinesUC != NULL)
+			ScreenLinesUC[off] = 0;
+		    int popup_attr_val = get_wcr_attr(screen_opacity_popup);
+		    int blend = screen_opacity_popup->w_popup_blend;
+		    ScreenAttrs[off] = hl_blend_attr(ScreenAttrs[off],
+				    popup_attr_val, blend, TRUE);
+		    popup_set_base_screen_cell(row, col, ScreenLines[off],
+					       ScreenAttrs[off], ScreenLinesUC[off]);
+		    screen_char(off, row, col);
+		    return;
+		}
+
+		// Base cell is inside the saved area, redraw the wide char.
+		if (save_off > 0)
+		{
+		    ScreenLines[base_off] = saved_screenlines[base_save_off];
+		    ScreenAttrs[base_off] = saved_screenattrs[base_save_off];
+		    ScreenLines[off] = saved_screenlines[save_off];
+		    ScreenAttrs[off] = saved_screenattrs[save_off];
+		    ScreenLinesUC[base_off] = saved_screenlinesuc[base_save_off];
+		    ScreenLinesUC[off] = saved_screenlinesuc[save_off];
+
+		    int popup_attr_val = get_wcr_attr(screen_opacity_popup);
+		    int blend = screen_opacity_popup->w_popup_blend;
+		    ScreenAttrs[base_off] = hl_blend_attr(ScreenAttrs[base_off],
+				    popup_attr_val, blend, TRUE);
+		    ScreenAttrs[off] = ScreenAttrs[base_off];
+		    popup_set_base_screen_cell(row, base_col, ScreenLines[base_off],
+					       ScreenAttrs[base_off], ScreenLinesUC[base_off]);
+		    popup_set_base_screen_cell(row, col, ScreenLines[off],
+					       ScreenAttrs[off], ScreenLinesUC[off]);
+		    screen_char(base_off, row, base_col);
+		}
+		return;
+	    }
+	}
 	ScreenLines[off] = saved_screenlines[save_off];
 	ScreenAttrs[off] = saved_screenattrs[save_off];
 	if (enc_utf8 && saved_screenlinesuc != NULL)
 	    ScreenLinesUC[off] = saved_screenlinesuc[save_off];
+
+	// If the saved character is wide and would extend past the padding
+	// area into the content area, replace with a space to avoid
+	// corrupting the content.
+	if (enc_utf8 && ScreenLinesUC[off] != 0
+		&& utf_char2cells(ScreenLinesUC[off]) == 2
+		&& col + 1 >= pad_end_col)
+	{
+	    ScreenLines[off] = ' ';
+	    ScreenLinesUC[off] = 0;
+	}
+
 	int popup_attr_val = get_wcr_attr(screen_opacity_popup);
 	int blend = screen_opacity_popup->w_popup_blend;
 	ScreenAttrs[off] = hl_blend_attr(ScreenAttrs[off],
 				popup_attr_val, blend, TRUE);
+	popup_set_base_screen_cell(row, col, ScreenLines[off],
+				   ScreenAttrs[off], ScreenLinesUC[off]);
 	screen_char(off, row, col);
     }
 }
@@ -4278,7 +4569,7 @@ draw_opacity_padding_cell(
 /*
  * Fill a rectangular padding area with opacity blending.
  */
-    static void
+static void
 fill_opacity_padding(
 	int		start_row,
 	int		end_row,
@@ -4296,7 +4587,8 @@ fill_opacity_padding(
 	for (int pad_col = start_col; pad_col < end_col; pad_col++)
 	    draw_opacity_padding_cell(pad_row, pad_col,
 		    saved_screenlines, saved_screenattrs, saved_screenlinesuc,
-		    save_start_row, save_start_col, save_rows, save_cols);
+		    save_start_row, save_start_col, save_rows, save_cols,
+		    start_col, end_col);
 }
 
 /*
@@ -4333,6 +4625,25 @@ update_popups(void (*win_update)(win_T *wp))
     // so that the window with a higher zindex is drawn later, thus goes on
     // top.
     popup_reset_handled(POPUP_HANDLED_5);
+#ifdef FEAT_PROP_POPUP
+    if (base_screenlines != NULL)
+    {
+	vim_free(base_screenlines);
+	base_screenlines = NULL;
+    }
+    if (base_screenattrs != NULL)
+    {
+	vim_free(base_screenattrs);
+	base_screenattrs = NULL;
+    }
+    if (base_screenlinesuc != NULL)
+    {
+	vim_free(base_screenlinesuc);
+	base_screenlinesuc = NULL;
+    }
+    base_screen_rows = 0;
+    base_screen_cols = 0;
+#endif
     while ((wp = find_next_popup(TRUE, POPUP_HANDLED_5)) != NULL)
     {
 	int	    title_len = 0;
@@ -4350,6 +4661,54 @@ update_popups(void (*win_update)(win_T *wp))
 	else
 	    screen_opacity_popup = NULL;
 
+#ifdef FEAT_PROP_POPUP
+	if (screen_opacity_popup != NULL)
+	{
+	    if (base_screenlines != NULL)
+	    {
+		vim_free(base_screenlines);
+		base_screenlines = NULL;
+	    }
+	    if (base_screenattrs != NULL)
+	    {
+		vim_free(base_screenattrs);
+		base_screenattrs = NULL;
+	    }
+	    if (base_screenlinesuc != NULL)
+	    {
+		vim_free(base_screenlinesuc);
+		base_screenlinesuc = NULL;
+	    }
+
+	    base_screen_rows = screen_Rows;
+	    base_screen_cols = screen_Columns;
+	    base_screenlines = ALLOC_MULT(schar_T,
+				    base_screen_rows * base_screen_cols);
+	    base_screenattrs = ALLOC_MULT(int,
+				    base_screen_rows * base_screen_cols);
+	    if (enc_utf8)
+		base_screenlinesuc = ALLOC_MULT(u8char_T,
+				    base_screen_rows * base_screen_cols);
+
+	    if (base_screenlines != NULL && base_screenattrs != NULL)
+	    {
+		for (int r = 0; r < base_screen_rows; r++)
+		{
+		    int off = LineOffset[r];
+		    int base_off = r * base_screen_cols;
+		    for (int c = 0; c < base_screen_cols; c++)
+		    {
+			base_screenlines[base_off + c] = ScreenLines[off + c];
+			base_screenattrs[base_off + c] = ScreenAttrs[off + c];
+			if (enc_utf8 && base_screenlinesuc != NULL)
+			    base_screenlinesuc[base_off + c] =
+					ScreenLinesUC[off + c];
+		    }
+		}
+	    }
+	}
+#endif
+
 	// Save background ScreenLines for padding opacity.
 	// We need to save it before win_update() overwrites it.
 	schar_T *saved_screenlines = NULL;
@@ -4370,6 +4729,14 @@ update_popups(void (*win_update)(win_T *wp))
 	    save_rows = wp->w_popup_padding[0] + wp->w_height + wp->w_popup_padding[2];
 	    save_cols = wp->w_popup_padding[3] + wp->w_width + wp->w_popup_padding[1];
 
+	    // Include one column to the left to handle wide chars that overlap
+	    // the padding boundary.
+	    if (save_start_col > 0)
+	    {
+		--save_start_col;
+		++save_cols;
+	    }
+
 	    // Allocate buffers
 	    saved_screenlines = ALLOC_MULT(schar_T, save_rows * save_cols);
 	    saved_screenattrs = ALLOC_MULT(int, save_rows * save_cols);
@@ -4686,8 +5053,16 @@ update_popups(void (*win_update)(win_T *wp))
 		    col = 0;
 		}
 		if (pad_left > 0)
-		    screen_fill(row, row + 1, col, col + pad_left,
+		{
+		    if (screen_opacity_popup != NULL && saved_screenlines != NULL)
+			fill_opacity_padding(row, row + 1, col, col + pad_left,
+				saved_screenlines, saved_screenattrs,
+				saved_screenlinesuc, save_start_row,
+				save_start_col, save_rows, save_cols);
+		    else
+			screen_fill(row, row + 1, col, col + pad_left,
 							 ' ', ' ', popup_attr);
+		}
 	    }
 	    // scrollbar
 	    if (wp->w_has_scrollbar)
@@ -4717,7 +5092,13 @@ update_popups(void (*win_update)(win_T *wp))
 			+ wp->w_popup_padding[3] + wp->w_width + wp->w_leftcol;
 		int pad_col_end = pad_col_start + wp->w_popup_padding[1];
 
-		screen_fill(row, row + 1, pad_col_start, pad_col_end,
+		if (screen_opacity_popup != NULL && saved_screenlines != NULL)
+		    fill_opacity_padding(row, row + 1, pad_col_start, pad_col_end,
+			    saved_screenlines, saved_screenattrs,
+			    saved_screenlinesuc, save_start_row, save_start_col,
+			    save_rows, save_cols);
+		else
+		    screen_fill(row, row + 1, pad_col_start, pad_col_end,
 							     ' ', ' ', popup_attr);
 	    }
 	}
@@ -4805,6 +5186,26 @@ update_popups(void (*win_update)(win_T *wp))
 #endif
     }
 
+#ifdef FEAT_PROP_POPUP
+    if (base_screenlines != NULL)
+    {
+	vim_free(base_screenlines);
+	base_screenlines = NULL;
+    }
+    if (base_screenattrs != NULL)
+    {
+	vim_free(base_screenattrs);
+	base_screenattrs = NULL;
+    }
+    if (base_screenlinesuc != NULL)
+    {
+	vim_free(base_screenlinesuc);
+	base_screenlinesuc = NULL;
+    }
+    base_screen_rows = 0;
+    base_screen_cols = 0;
+#endif
+
 #if defined(FEAT_SEARCH_EXTRA)
     // In case win_update() called start_search_hl().
     end_search_hl();

src/proto/popupwin.pro

@@ -16,6 +16,7 @@ int parse_completepopup(win_T *wp);
 void popup_set_wantpos_cursor(win_T *wp, int width, dict_T *d);
 void popup_set_wantpos_rowcol(win_T *wp, int row, int col);
 void popup_redraw_all(void);
+int popup_need_redraw(void);
 void f_popup_clear(typval_T *argvars, typval_T *rettv);
 void f_popup_create(typval_T *argvars, typval_T *rettv);
 void f_popup_atcursor(typval_T *argvars, typval_T *rettv);
@@ -53,6 +54,8 @@ int popup_no_mapping(void);
 void popup_check_cursor_pos(void);
 void may_update_popup_mask(int type);
 void may_update_popup_position(void);
+int popup_get_base_screen_cell(int row, int col, schar_T *linep, int *attrp, u8char_T *ucp);
+void popup_set_base_screen_cell(int row, int col, schar_T line, int attr, u8char_T uc);
 void update_popups(void (*win_update)(win_T *wp));
 int set_ref_in_popups(int copyID);
 int popup_is_popup(win_T *wp);

src/screen.c

@@ -627,6 +627,7 @@ screen_line(
 		&& ScreenLines[off_from] == ' '
 		&& (!enc_utf8 || ScreenLinesUC[off_from] == 0)
 		&& ScreenLines[off_to] == 0
+		&& (!enc_utf8 || ScreenLinesUC[off_to] == 0)
 		&& off_to > 0
 		&& enc_utf8 && ScreenLinesUC[off_to - 1] != 0
 		&& utf_char2cells(ScreenLinesUC[off_to - 1]) == 2)
@@ -639,7 +640,8 @@ screen_line(
 		&& (flags & SLF_POPUP)
 		&& ScreenLines[off_from] == ' '
 		&& (!enc_utf8 || ScreenLinesUC[off_from] == 0)
-		&& ScreenLines[off_to] != 0)
+		&& (ScreenLines[off_to] != 0
+		    || (enc_utf8 && ScreenLinesUC[off_to] != 0)))
 	{
 	    int bg_char_cells = 1;
 	    if (enc_utf8 && ScreenLinesUC[off_to] != 0)
@@ -652,8 +654,23 @@ screen_line(
 	    {
 		if (col + 1 >= endcol || off_from + 1 >= max_off_from
 						   || off_to + 1 >= max_off_to)
-		    // At the edge of the screen, skip wide char.
+		{
+		    // Wide char doesn't fit at the edge.  Replace with a
+		    // blended space so opacity is still applied.
+		    int char_attr = ScreenAttrs[off_from];
+		    int popup_attr = get_wcr_attr(screen_opacity_popup);
+		    int combined = hl_combine_attr(popup_attr, char_attr);
+		    int blend = screen_opacity_popup->w_popup_blend;
+		    ScreenLines[off_to] = ' ';
+		    if (enc_utf8)
+			ScreenLinesUC[off_to] = 0;
+		    ScreenAttrs[off_to] = hl_blend_attr(ScreenAttrs[off_to],
+						    combined, blend, TRUE);
+		    screen_char(off_to, row, col + coloff);
+		    opacity_blank = TRUE;
+		    redraw_this = FALSE;
 		    goto skip_opacity;
+		}
 		int next_off_from = off_from + 1;
 		if (!(ScreenLines[next_off_from] == ' '
 			&& (!enc_utf8 || ScreenLinesUC[next_off_from] == 0)))
@@ -681,6 +698,30 @@ screen_line(
 		ScreenAttrs[off_to + 1] = ScreenAttrs[off_to];
 	    redraw_this = FALSE;
 	}
+	// When a popup space overlaps the second half of a destroyed wide
+	// character (e.g., the first half was overwritten by popup content),
+	// the underlying cell has ScreenLines == 0 and no valid wide char
+	// at the previous cell.  Apply opacity blending so that the cell
+	// matches surrounding opacity-blended cells instead of appearing
+	// as a solid-colored gap.
+	else if (screen_opacity_popup != NULL
+		&& (flags & SLF_POPUP)
+		&& ScreenLines[off_from] == ' '
+		&& (!enc_utf8 || ScreenLinesUC[off_from] == 0)
+		&& ScreenLines[off_to] == 0
+		&& (!enc_utf8 || ScreenLinesUC[off_to] == 0))
+	{
+	    int char_attr = ScreenAttrs[off_from];
+	    int popup_attr = get_wcr_attr(screen_opacity_popup);
+	    int combined = hl_combine_attr(popup_attr, char_attr);
+	    int blend = screen_opacity_popup->w_popup_blend;
+	    ScreenLines[off_to] = ' ';
+	    ScreenAttrs[off_to] = hl_blend_attr(ScreenAttrs[off_to],
+						combined, blend, TRUE);
+	    screen_char(off_to, row, col + coloff);
+	    opacity_blank = TRUE;
+	    redraw_this = FALSE;
+	}
 skip_opacity:
 #endif
 
@@ -784,7 +825,11 @@ skip_opacity:
 		}
 	    }
 	    if (char_cells == 2)
+	    {
 		ScreenLines[off_to + 1] = ScreenLines[off_from + 1];
+		if (enc_utf8)
+		    ScreenLinesUC[off_to + 1] = 0;
+	    }
 
 #if defined(FEAT_GUI) || defined(UNIX)
 	    // The bold trick makes a single column of pixels appear in the

src/structs.h

@@ -4085,6 +4085,7 @@ struct window_S
     int		w_popup_padding[4]; // popup padding top/right/bot/left
     int		w_popup_border[4];  // popup border top/right/bot/left
     char_u	*w_border_highlight[4];  // popup border highlight
+    int		w_border_highlight_isset; // borderhighlight was explicitly set
     int		w_border_char[8];   // popup border characters
     int		w_popup_shadow;     // popup shadow (right and bottom edges)
 

src/testdir/dumps/Test_popupwin_mask_5.dump

@@ -10,4 +10,4 @@
 |1|2|3|4|5|6|7|8|9|1|0|1@2|2|1|3|1|4|1|5|1|6|1|7|1|8|1|9|2|0|2|1|2@2|3|2|4|2|5|2|6|2|7|2|8|2|9|3|0|3|1|3|2|3@2|4|3|5|3|6|3|7|3|8|3|9|4|0|4|1|4|2
 | +0&#e0e0e08@11|1+0&#ffffff0@1|2|1|3|1|4|1|5|1|6|1|7|1|8|1|9|2|0|2|1|2@2|3|2|4|2|5|2|6|═+0#0000001#ffd7ff255@13|X|4+0#0000000#ffffff0|3|5|3|6|3|7|3|8|3|9|4|0|4|1|4|2
 |o+0&#e0e0e08|m|e| |t|e|x|t| @3|1+0&#ffffff0@1|2|1|3|1|4|1|5|1|6|1|7|1|8|1|9|2|0|2|1|2@2|3|2|4|2|5|║+0#0000001#ffd7ff255| @4|2+0#0000000#ffffff0|9|3| +0#0000001#ffd7ff255@6|║|4+0#0000000#ffffff0|3|5|3|6|3|7|3|8|3|9|4|0|4|1|4|2
-|n+0&#e0e0e08|o|t|h|e|r| |l|i|n|e| | +0&#ffffff0@28|║+0#0000001#ffd7ff255| |j|u|s|t| |o|n|e| |l|i|n|e| |║|,+0#0000000#ffffff0|1| @10|T|o|p| 
+|:| |t+0&#e0e0e08|h| +0&#ffffff0@2|l+0&#e0e0e08|i|n|e| | +0&#ffffff0@28|║+0#0000001#ffd7ff255| |j|u|s|t| +0#0000000#ffffff0@2|e+0#0000001#ffd7ff255| |l|i|n|e| |║|,+0#0000000#ffffff0|1| @10|T|o|p| 

src/testdir/dumps/Test_popupwin_opacity_wide_1.dump

@@ -0,0 +1,15 @@
+>い*0&#ffffff0|え|ー@15|い|!+&| |1| @3
+|い*&|え|ー@15|い|!+&| |2| @3
+|い*&|え|ー@15|い|!+&| |3| @3
+|い*&|え*0#ffffff16#e000002|ー@6| |ー*0#0000000#ffffff0@7|い|!+&| |4| @3
+|い*&| +0#ffffff16#e000002|カ*&|ラ|フ|ル|な| +&|ー*&@1| |ー*0#0000000#ffffff0@7|い|!+&| |5| @3
+|い*&| +0#ffffff16#e000002|ポ*&|ッ|プ|ア|ッ|プ|で|─+&|╮| +0#0000000#ffffff0|ー*&@7|い|!+&| |6| @3
+|い*&| +0#ffffff16#e000002|最*&|上|川| +&|ぼ*&|赤|い|な|│+&| +0#0000000#ffffff0|ー*&@7|い|!+&| |7| @3
+|い*&| +0#ffffff16#e000002|│|あ*&|い|う|え|お|ー@1|│+&| +0#0000000#ffffff0|ー*&@7|い|!+&| |8| @3
+|い*&| +&|│+0#ffffff16#0000e05|ー*&@6|│+&| +0#0000000#ffffff0|ー*&@7|い|!+&| |9| @3
+|い*&| +&|╰+0#ffffff16#0000e05|─@13|╯| +0#0000000#ffffff0|ー*&@7|い|!+&| |1|0| @2
+|い*&|え|ー@15|い|!+&| |1@1| @2
+|い*&|え|ー@15|い|!+&| |1|2| @2
+|い*&|え|ー@15|い|!+&| |1|3| @2
+|い*&|え|ー@15|い|!+&| |1|4| @2
+@27|1|,|1| @10|T|o|p| 

src/testdir/dumps/Test_popupwin_opacity_wide_2.dump

@@ -0,0 +1,15 @@
+>い*0&#ffffff0|え|ー@15|い|!+&| |1| @3
+|い*&|え|ー@15|い|!+&| |2| @3
+|い*&|え|ー@15|い|!+&| |3| @3
+|い*&|え|ー@15|い|!+&| |4| @3
+|い*&|え|ー@15|い|!+&| |5| @3
+|い*&| +&|╭+0#ffffff16#0000e05|─@13|╮| +0#0000000#ffffff0|ー*&@7|い|!+&| |6| @3
+|い*&| +&|│+0#ffffff16#0000e05|あ*&|め|ん|ぼ|赤|い|な|│+&| +0#0000000#ffffff0|ー*&@7|い|!+&| |7| @3
+|い*&| +&|│+0#ffffff16#0000e05|あ*&|い|う|え|お| +&| +0&#e000002|ー*&|│+&| |ー*&@5|ー*0#0000000#ffffff0@1|い|!+&| |8| @3
+|い*&| +&|│+0#ffffff16#0000e05|ー*&@4| +&| +0&#e000002|カ*&|ラ|フ|ル|な|ー@2|ー*0#0000000#ffffff0@1|い|!+&| |9| @3
+|い*&| +&|╰+0#ffffff16#0000e05|─@10|─+0&#e000002|ポ*&|ッ|プ|ア|ッ|プ|で|ー|ー*0#0000000#ffffff0@1|い|!+&| |1|0| @2
+|い*&|え|ー@4| +&| +0#ffffff16#e000002|最*&|上|川|ー@4|ー*0#0000000#ffffff0@1|い|!+&| |1@1| @2
+|い*&|え|ー@4| +&| +0#ffffff16#e000002|ー*&@7|ー*0#0000000#ffffff0@1|い|!+&| |1|2| @2
+|い*&|え|ー@15|い|!+&| |1|3| @2
+|い*&|え|ー@15|い|!+&| |1|4| @2
+|:| @25|1|,|1| @10|T|o|p| 

src/testdir/test_popupwin.vim

@@ -176,6 +176,11 @@ func Test_popup_with_border_and_padding()
   call popup_setoptions(winid, options)
   call assert_equal(options, popup_getoptions(winid))
 
+  " Check that borderhighlight can be cleared with empty list
+  call popup_setoptions(winid, #{borderhighlight: []})
+  let options_cleared = popup_getoptions(winid)
+  call assert_equal([], options_cleared.borderhighlight)
+
   " Check that range() doesn't crash
   call popup_setoptions(winid, #{
 	\ padding: range(1, 4),
@@ -4845,4 +4850,53 @@ func Test_popup_getwininfo_tabnr()
   tabonly
 endfunc
 
+func Test_popup_opacity_wide_char_overlap()
+  CheckScreendump
+
+  " Two overlapping popups with opacity over wide-character background.
+  " Verifies that wide characters at the content/padding boundary of the
+  " higher-zindex popup are properly blended (no holes or missing chars).
+  let lines =<< trim END
+    set encoding=utf-8
+    for i in range(1, 20)
+      call setline(i, 'いえーーーーーーーーーーーーーーーーい! ' .. i)
+    endfor
+    hi MyPopup1 ctermbg=darkblue ctermfg=white
+    hi MyPopup2 ctermbg=darkred ctermfg=white
+    let g:p1 = popup_create(['あめんぼ赤いな','あいうえお'], #{
+        \ opacity: 50,
+        \ line: 6,
+        \ col: 4,
+        \ border: [],
+        \ borderchars: ['─','│','─','│','╭','╮','╯','╰'],
+        \ minwidth: 14,
+        \ minheight: 3,
+        \ highlight: 'MyPopup1',
+        \ zindex: 1,
+        \})
+    let g:p2 = popup_create(['カラフルな','ポップアップで','最上川'], #{
+        \ opacity: 50,
+        \ line: 4,
+        \ col: 3,
+        \ minwidth: 15,
+        \ minheight: 3,
+        \ padding: [1,1,1,1],
+        \ highlight: 'MyPopup2',
+        \ zindex: 2,
+        \})
+  END
+  call writefile(lines, 'XtestPopupOpacityWide', 'D')
+  let buf = RunVimInTerminal('-S XtestPopupOpacityWide', #{rows: 15, cols: 45})
+  call VerifyScreenDump(buf, 'Test_popupwin_opacity_wide_1', {})
+
+  " Move popups far apart so they don't overlap.
+  " Tests right edge of popup where wide chars span content/padding boundary.
+  call term_sendkeys(buf, ":call popup_move(g:p2, #{line: 14, col: 16})\<CR>")
+  call TermWait(buf)
+  call term_sendkeys(buf, ":\<CR>")
+  call VerifyScreenDump(buf, 'Test_popupwin_opacity_wide_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    80,
 /**/
     79,
 /**/