diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index c77f38a693..b44b86db7b 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -3198,10 +3198,15 @@ nvim_open_win({buffer}, {enter}, {config})                   *nvim_open_win()*
                     entered by |nvim_set_current_win()|, or, when the `mouse`
                     field is set to true, by mouse events.
                   • mouse: Specify how this window interacts with mouse
-                    events. Defaults to `focusable` value.
+                    events. May be a boolean or a Lua callback. Defaults to
+                    `focusable` value.
                     • If false, mouse events pass through this window.
                     • If true, mouse events interact with this window
                       normally.
+                    • If a Lua callback, mouse events interact with this
+                      window, but the callback is called in place of the
+                      default handling. The default handling will be used
+                      again if callback returns `true`.
                   • external: GUI should display the window as an external
                     top-level window. Currently accepts no other positioning
                     configuration together with this.
diff --git a/runtime/lua/vim/_meta/api.lua b/runtime/lua/vim/_meta/api.lua
index 8236cc7cf0..797d7ce66d 100644
--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@@ -1770,9 +1770,12 @@ function vim.api.nvim_open_term(buffer, opts) end
 ---     `nvim_set_current_win()`, or, when the `mouse` field is set to true,
 ---     by mouse events.
 --- - mouse: Specify how this window interacts with mouse events.
----     Defaults to `focusable` value.
+---     May be a boolean or a Lua callback. Defaults to `focusable` value.
 ---     - If false, mouse events pass through this window.
 ---     - If true, mouse events interact with this window normally.
+---     - If a Lua callback, mouse events interact with this window,
+---       but the callback is called in place of the default handling.
+---       The default handling will be used again if callback returns `true`.
 --- - external: GUI should display the window as an external
 ---     top-level window. Currently accepts no other positioning
 ---     configuration together with this.
diff --git a/runtime/lua/vim/_meta/api_keysets.lua b/runtime/lua/vim/_meta/api_keysets.lua
index bf184dee2d..508d230265 100644
--- a/runtime/lua/vim/_meta/api_keysets.lua
+++ b/runtime/lua/vim/_meta/api_keysets.lua
@@ -295,7 +295,7 @@ error('Cannot require a meta file')
 --- @field bufpos? any[]
 --- @field external? boolean
 --- @field focusable? boolean
---- @field mouse? boolean
+--- @field mouse? any
 --- @field vertical? boolean
 --- @field zindex? integer
 --- @field border? any
diff --git a/src/nvim/api/keysets_defs.h b/src/nvim/api/keysets_defs.h
index 96aabb851f..4aa3a9a487 100644
--- a/src/nvim/api/keysets_defs.h
+++ b/src/nvim/api/keysets_defs.h
@@ -119,7 +119,7 @@ typedef struct {
   Array bufpos;
   Boolean external;
   Boolean focusable;
-  Boolean mouse;
+  Object mouse;
   Boolean vertical;
   Integer zindex;
   Object border;
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index 16811e0cd9..2a064063dc 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -1,3 +1,4 @@
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <string.h>
 
@@ -23,6 +24,7 @@
 #include "nvim/globals.h"
 #include "nvim/grid_defs.h"
 #include "nvim/highlight_group.h"
+#include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
@@ -132,9 +134,12 @@
 ///       |nvim_set_current_win()|, or, when the `mouse` field is set to true,
 ///       by mouse events.
 ///   - mouse: Specify how this window interacts with mouse events.
-///       Defaults to `focusable` value.
+///       May be a boolean or a Lua callback. Defaults to `focusable` value.
 ///       - If false, mouse events pass through this window.
 ///       - If true, mouse events interact with this window normally.
+///       - If a Lua callback, mouse events interact with this window,
+///         but the callback is called in place of the default handling.
+///         The default handling will be used again if callback returns `true`.
 ///   - external: GUI should display the window as an external
 ///       top-level window. Currently accepts no other positioning
 ///       configuration together with this.
@@ -719,7 +724,18 @@ Dict(win_config) nvim_win_get_config(Window window, Arena *arena, Error *err)
   PUT_KEY_X(rv, focusable, config->focusable);
   PUT_KEY_X(rv, external, config->external);
   PUT_KEY_X(rv, hide, config->hide);
-  PUT_KEY_X(rv, mouse, config->mouse);
+
+  switch (config->mouse) {
+  case kWinMouseIgnore:
+    PUT_KEY_X(rv, mouse, BOOLEAN_OBJ(false));
+    break;
+  case kWinMouseDefault:
+    PUT_KEY_X(rv, mouse, BOOLEAN_OBJ(true));
+    break;
+  case kWinMouseCallback:
+    PUT_KEY_X(rv, mouse, LUAREF_OBJ(api_new_luaref(config->mouse_cb)));
+    break;
+  }
 
   if (wp->w_floating) {
     PUT_KEY_X(rv, width, config->width);
@@ -1208,11 +1224,22 @@ static bool parse_win_config(win_T *wp, Dict(win_config) *config, WinConfig *fco
 
   if (HAS_KEY_X(config, focusable)) {
     fconfig->focusable = config->focusable;
-    fconfig->mouse = config->focusable;
+    if (fconfig->mouse != kWinMouseCallback) {
+      fconfig->mouse = config->focusable ? kWinMouseDefault : kWinMouseIgnore;
+    }
   }
 
   if (HAS_KEY_X(config, mouse)) {
-    fconfig->mouse = config->mouse;
+    if (config->mouse.type == kObjectTypeLuaRef) {
+      fconfig->mouse = kWinMouseCallback;
+      fconfig->mouse_cb = config->mouse.data.luaref;
+      config->mouse.data.luaref = LUA_NOREF;
+    } else if (config->mouse.type == kObjectTypeBoolean) {
+      fconfig->mouse = config->mouse.data.boolean ? kWinMouseDefault : kWinMouseIgnore;
+      fconfig->mouse_cb = LUA_NOREF;
+    } else {
+      api_set_error(err, kErrorTypeValidation, "invalid type for 'mouse'");
+    }
   }
 
   if (HAS_KEY_X(config, zindex)) {
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 1fe5512708..b428551e52 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -904,6 +905,12 @@ typedef enum {
   kFloatRelativeMouse = 3,
 } FloatRelative;
 
+typedef enum {
+  kWinMouseIgnore = 0,
+  kWinMouseDefault = 1,
+  kWinMouseCallback = 2,
+} WinMouseEvent;
+
 /// Keep in sync with win_split_str[] in nvim_win_get_config() (api/win_config.c)
 typedef enum {
   kWinSplitLeft = 0,
@@ -938,7 +945,8 @@ typedef struct {
   FloatRelative relative;
   bool external;
   bool focusable;
-  bool mouse;
+  WinMouseEvent mouse;
+  LuaRef mouse_cb;
   WinSplit split;
   int zindex;
   WinStyle style;
@@ -965,7 +973,8 @@ typedef struct {
                                       .row = 0, .col = 0, .anchor = 0, \
                                       .relative = 0, .external = false, \
                                       .focusable = true, \
-                                      .mouse = true, \
+                                      .mouse = kWinMouseDefault, \
+                                      .mouse_cb = LUA_NOREF, \
                                       .split = 0, \
                                       .zindex = kZIndexFloatDefault, \
                                       .style = kWinStyleUnused, \
diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index 1289adfabb..b1e9a5ead9 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -4,6 +4,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "nvim/api/private/defs.h"
+#include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/buffer.h"
 #include "nvim/buffer_defs.h"
@@ -13,6 +15,7 @@
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/window.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/fold.h"
 #include "nvim/getchar.h"
@@ -20,6 +23,7 @@
 #include "nvim/grid.h"
 #include "nvim/grid_defs.h"
 #include "nvim/keycodes.h"
+#include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mark_defs.h"
 #include "nvim/mbyte.h"
@@ -222,6 +226,45 @@ static void call_click_def_func(StlClickDefinition *click_defs, int col, int whi
   got_click = false;
 }
 
+/// When mouse events happen in a window with a mouse callback, invoke it.
+///
+/// @param  button  !is_scroll: return value of get_mouse_button()
+///                 is_scroll: a MSCR_* enum
+///
+/// @return  whether to proceeded with mouse handling.
+static bool handle_mouse_cb(bool is_click, bool is_drag, bool is_scroll, int button)
+{
+  static handle_T last_click_win = 0;
+  int grid = mouse_grid;
+  int row = mouse_row;
+  int col = mouse_col;
+
+  win_T *wp = NULL;
+  if (!is_click && !is_scroll && button != MOUSE_RELEASE) {  // drag or release
+    if (last_click_win > 0) {
+      wp = win_id2wp(last_click_win);
+    }
+  } else {  // click, scroll or move
+    wp = mouse_find_win(&grid, &row, &col);
+    if (is_click) {
+      last_click_win = wp != NULL ? wp->handle : 0;
+    }
+  }
+  if (wp == NULL || wp->w_config.mouse != kWinMouseCallback) {
+    return true;
+  }
+
+  Error err = ERROR_INIT;
+  Object res = nlua_call_ref(wp->w_config.mouse_cb, NULL, (Array)ARRAY_DICT_INIT,
+                             kRetNilBool, NULL, &err);
+  bool retval = LUARET_TRUTHY(res);
+  if (ERROR_SET(&err)) {
+    semsg_multiline("E5108: %s", err.msg);
+    api_clear_error(&err);
+  }
+  return retval;
+}
+
 /// Translate window coordinates to buffer position without any side effects.
 /// Returns IN_BUFFER and sets "mpos->col" to the column when in buffer text.
 /// The column is one for the first column.
@@ -371,6 +414,10 @@ bool do_mouse(oparg_T *oap, int c, int dir, int count, bool fixindent)
     break;
   }
 
+  if (!handle_mouse_cb(is_click, is_drag, false, which_button)) {
+    return false;
+  }
+
   if (c == K_MOUSEMOVE) {
     // Mouse moved without a button pressed.
     return false;
@@ -1063,6 +1110,10 @@ void do_mousescroll(cmdarg_T *cap)
 /// of the MSCR_ values.
 void ins_mousescroll(int dir)
 {
+  if (!handle_mouse_cb(false, false, true, dir)) {
+    return;
+  }
+
   cmdarg_T cap;
   oparg_T oa;
   CLEAR_FIELD(cap);
@@ -1572,6 +1623,10 @@ static bool do_mousescroll_horiz(colnr_T leftcol)
 /// "cap->arg", which is one of the MSCR_ values.
 void nv_mousescroll(cmdarg_T *cap)
 {
+  if (!handle_mouse_cb(false, false, true, cap->arg)) {
+    return;
+  }
+
   win_T *const old_curwin = curwin;
 
   if (mouse_row >= 0 && mouse_col >= 0) {
@@ -1740,7 +1795,7 @@ static win_T *mouse_find_grid_win(int *gridp, int *rowp, int *colp)
   } else if (*gridp > 1) {
     win_T *wp = get_win_by_grid_handle(*gridp);
     if (wp && wp->w_grid_alloc.chars
-        && !(wp->w_floating && !wp->w_config.mouse)) {
+        && !(wp->w_floating && wp->w_config.mouse == kWinMouseIgnore)) {
       *rowp = MIN(*rowp - wp->w_grid.row_offset, wp->w_grid.rows - 1);
       *colp = MIN(*colp - wp->w_grid.col_offset, wp->w_grid.cols - 1);
       return wp;
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 91a69c3ec4..18a835159d 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -45,6 +45,7 @@
 #include "nvim/grid_defs.h"
 #include "nvim/hashtab.h"
 #include "nvim/keycodes.h"
+#include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
 #include "nvim/main.h"
 #include "nvim/map_defs.h"
@@ -802,6 +803,9 @@ int win_fdccol_count(win_T *wp)
 void merge_win_config(WinConfig *dst, const WinConfig src)
   FUNC_ATTR_NONNULL_ALL
 {
+  if (dst->mouse_cb != src.mouse_cb) {
+    api_free_luaref(dst->mouse_cb);
+  }
   if (dst->title_chunks.items != src.title_chunks.items) {
     clear_virttext(&dst->title_chunks);
   }
@@ -857,7 +861,7 @@ void ui_ext_win_position(win_T *wp, bool validate)
       String anchor = cstr_as_string(float_anchor_str[c.anchor]);
       if (!c.hide) {
         ui_call_win_float_pos(wp->w_grid_alloc.handle, wp->handle, anchor,
-                              grid->handle, row, col, c.mouse,
+                              grid->handle, row, col, c.mouse != kWinMouseIgnore,
                               wp->w_grid_alloc.zindex);
       } else {
         ui_call_win_hide(wp->w_grid_alloc.handle);
@@ -889,7 +893,7 @@ void ui_ext_win_position(win_T *wp, bool validate)
         ui_comp_put_grid(&wp->w_grid_alloc, comp_row, comp_col,
                          wp->w_height_outer, wp->w_width_outer, valid, false);
         ui_check_cursor_grid(wp->w_grid_alloc.handle);
-        wp->w_grid_alloc.mouse_enabled = wp->w_config.mouse;
+        wp->w_grid_alloc.mouse_enabled = wp->w_config.mouse != kWinMouseIgnore;
         if (!valid) {
           wp->w_grid_alloc.valid = false;
           redraw_later(wp, UPD_NOT_VALID);
@@ -4044,7 +4048,7 @@ void win_alloc_aucmd_win(int idx)
   fconfig.width = Columns;
   fconfig.height = 5;
   fconfig.focusable = false;
-  fconfig.mouse = false;
+  fconfig.mouse = kWinMouseIgnore;
   aucmd_win[idx].auc_win = win_new_float(NULL, true, fconfig, &err);
   aucmd_win[idx].auc_win->w_buffer->b_nwindows--;
   RESET_BINDING(aucmd_win[idx].auc_win);
@@ -5263,9 +5267,8 @@ void win_free(win_T *wp, tabpage_T *tp)
     }
   }
 
-  // free the border text
-  clear_virttext(&wp->w_config.title_chunks);
-  clear_virttext(&wp->w_config.footer_chunks);
+  // free allocated resources in w_config
+  merge_win_config(&wp->w_config, WIN_CONFIG_INIT);
 
   clear_matches(wp);
 
diff --git a/src/nvim/winfloat.c b/src/nvim/winfloat.c
index 054ef07fc5..c12399954f 100644
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -389,7 +389,7 @@ win_T *win_float_create(bool enter, bool new_buf)
   config.row = curwin->w_wrow;
   config.relative = kFloatRelativeEditor;
   config.focusable = false;
-  config.mouse = false;
+  config.mouse = kWinMouseIgnore;
   config.anchor = 0;  // NW
   config.noautocmd = true;
   config.hide = true;