Merge pull request #3871 from ZyX-I/tabline-clicks

Allow running random code on tabline clicks

12 files changed, 481 insertions, 149 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 766dafd1d7..e4311b3ba0 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -7063,6 +7063,7 @@ statusline		Compiled with support for 'statusline', 'rulerformat'
 syntax			Compiled with syntax highlighting support |syntax|.
 syntax_items		There are active syntax highlighting items for the
 			current buffer.
+tablineat		'tabline' option accepts %@Func@ items.
 tag_binary		Compiled with binary searching in tags files
 			|tag-binary-search|.
 tag_old_static		Compiled with support for old static tags
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index d9024b98c0..51bfc12f9d 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -6011,11 +6011,39 @@ A jump table for the options with a short description can be found at |Q_op|.
 	( -   Start of item group.  Can be used for setting the width and
 	      alignment of a section.  Must be followed by %) somewhere.
 	) -   End of item group.  No width fields allowed.
-	T N   For 'tabline': start of tab page N label.  Use %T after the last
-	      label.  This information is used for mouse clicks.
-	X N   For 'tabline': start of close tab N label.  Use %X after the
-	      label, e.g.: %3Xclose%X.  Use %999X for a "close current tab"
-	      mark.  This information is used for mouse clicks.
+	T N   For 'tabline': start of tab page N label.  Use %T or %X to end 
+	      the label.  Clicking this label with left mouse button switches 
+	      to the specified tab page.
+	X N   For 'tabline': start of close tab N label.  Use %X or %T to end 
+	      the label, e.g.: %3Xclose%X.  Use %999X for a "close current 
+	      tab" label.    Clicking this label with left mouse button closes 
+	      specified tab page.
+	@ N   For 'tabline': start of execute function label. Use %X or %T to 
+	      end the label, e.g.: %10@SwitchBuffer@foo.c%X.  Clicking this 
+	      label runs specified function: in the example when clicking once 
+	      using left mouse button on "foo.c" "SwitchBuffer(10, 1, 'l', 
+	      '    ')" expression will be run.  Function receives the 
+	      following arguments in order:
+	      1. minwid field value or zero if no N was specified
+	      2. number of mouse clicks to detect multiple clicks
+	      3. mouse button used: "l", "r" or "m" for left, right or middle 
+	         button respectively; one should not rely on third argument 
+	         being only "l", "r" or "m": any other non-empty string value 
+	         that contains only ASCII lower case letters may be expected 
+	         for other mouse buttons
+	      4. modifiers pressed: string which contains "s" if shift 
+	         modifier was pressed, "c" for control, "a" for alt and "m" 
+	         for meta; currently if modifier is not pressed string 
+	         contains space instead, but one should not rely on presence 
+	         of spaces or specific order of modifiers: use |stridx()| to 
+	         test whether some modifier is present; string is guaranteed 
+	         to contain only ASCII letters and spaces, one letter per 
+	         modifier; "?" modifier may also be present, but its presence 
+	         is a bug that denotes that new mouse button recognition was 
+	         added without modifying code that reacts on mouse clicks on 
+	         this label.
+	      Note: to test whether your version of Neovim contains this 
+	            feature use `has('tablineat')`.
 	< -   Where to truncate line if too long.  Default is at the start.
 	      No width fields allowed.
 	= -   Separation point between left and right aligned items.
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index 26ff8f0783..ff37466a14 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -363,6 +363,7 @@ N  *+startuptime*	|--startuptime| argument
 N  *+statusline*	Options 'statusline', 'rulerformat' and special
 			formats of 'titlestring' and 'iconstring'
 N  *+syntax*		Syntax highlighting |syntax|
+N  *+tablineat*		'tabline' option recognizing %@Func@ items.
 N  *+tag_binary*	binary searching in tags file |tag-binary-search|
 N  *+tag_old_static*	old method for static tags |tag-old-static|
 m  *+tag_any_white*	any white space allowed in tags file |tag-any-white|
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index a6e3fedd3f..34e24712cd 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -22,6 +22,7 @@
 
 #include "nvim/api/private/handle.h"
 #include "nvim/ascii.h"
+#include "nvim/assert.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
 #include "nvim/charset.h"
@@ -2826,7 +2827,7 @@ typedef enum {
 /// @param fillchar Character to use when filling empty space in the statusline
 /// @param maxwidth The maximum width to make the statusline
 /// @param hltab HL attributes (can be NULL)
-/// @param tabtab tab page nrs (can be NULL)
+/// @param tabtab Tab clicks definition (can be NULL).
 ///
 /// @return The final width of the statusline
 int build_stl_str_hl(
@@ -2838,13 +2839,15 @@ int build_stl_str_hl(
     int fillchar,
     int maxwidth,
     struct stl_hlrec *hltab,
-    struct stl_hlrec *tabtab
+    StlClickRecord *tabtab
 )
 {
   int groupitem[STL_MAX_ITEM];
   struct stl_item {
     // Where the item starts in the status line output buffer
-    char_u          *start;
+    char_u *start;
+    // Function to run for ClickFunc items.
+    char *cmd;
     // The minimum width of the item
     int minwid;
     // The maximum width of the item
@@ -2856,10 +2859,10 @@ int build_stl_str_hl(
       Middle,
       Highlight,
       TabPage,
+      ClickFunc,
       Trunc
-    }               type;
-  }           item[STL_MAX_ITEM];
-
+    } type;
+  } item[STL_MAX_ITEM];
 #define TMPLEN 70
   char_u tmp[TMPLEN];
   char_u      *usefmt = fmt;
@@ -3164,6 +3167,24 @@ int build_stl_str_hl(
       continue;
     }
 
+    if (*fmt_p == STL_CLICK_FUNC) {
+      fmt_p++;
+      char *t = (char *) fmt_p;
+      while (*fmt_p != STL_CLICK_FUNC && *fmt_p) {
+        fmt_p++;
+      }
+      if (*fmt_p != STL_CLICK_FUNC) {
+        break;
+      }
+      item[curitem].type = ClickFunc;
+      item[curitem].start = out_p;
+      item[curitem].cmd = xmemdupz(t, (size_t) (((char *) fmt_p - t)));
+      item[curitem].minwid = minwid;
+      fmt_p++;
+      curitem++;
+      continue;
+    }
+
     // Denotes the end of the minwid
     // the maxwid may follow immediately after
     if (*fmt_p == '.') {
@@ -3281,6 +3302,7 @@ int build_stl_str_hl(
       }
       break;
     }
+
     case STL_LINE:
       num = (wp->w_buffer->b_ml.ml_flags & ML_EMPTY)
             ? 0L : (long)(wp->w_cursor.lnum);
@@ -3821,16 +3843,37 @@ int build_stl_str_hl(
 
   // Store the info about tab pages labels.
   if (tabtab != NULL) {
-    struct stl_hlrec *sp = tabtab;
+    StlClickRecord *cur_tab_rec = tabtab;
     for (long l = 0; l < itemcnt; l++) {
       if (item[l].type == TabPage) {
-        sp->start = item[l].start;
-        sp->userhl = item[l].minwid;
-        sp++;
+        cur_tab_rec->start = (char *) item[l].start;
+        if (item[l].minwid == 0) {
+          cur_tab_rec->def.type = kStlClickDisabled;
+          cur_tab_rec->def.tabnr = 0;
+        } else {
+          int tabnr = item[l].minwid;
+          if (item[l].minwid > 0) {
+            cur_tab_rec->def.type = kStlClickTabSwitch;
+          } else {
+            cur_tab_rec->def.type = kStlClickTabClose;
+            tabnr = -tabnr;
+          }
+          cur_tab_rec->def.tabnr = tabnr;
+        }
+        cur_tab_rec->def.func = NULL;
+        cur_tab_rec++;
+      } else if (item[l].type == ClickFunc) {
+        cur_tab_rec->start = (char *) item[l].start;
+        cur_tab_rec->def.type = kStlClickFuncRun;
+        cur_tab_rec->def.tabnr = item[l].minwid;
+        cur_tab_rec->def.func = item[l].cmd;
+        cur_tab_rec++;
       }
     }
-    sp->start = NULL;
-    sp->userhl = 0;
+    cur_tab_rec->start = NULL;
+    cur_tab_rec->def.type = kStlClickDisabled;
+    cur_tab_rec->def.tabnr = 0;
+    cur_tab_rec->def.func = NULL;
   }
 
   return width;
diff --git a/src/nvim/buffer.h b/src/nvim/buffer.h
index 49025d3925..d51a2f7dae 100644
--- a/src/nvim/buffer.h
+++ b/src/nvim/buffer.h
@@ -4,6 +4,7 @@
 #include "nvim/window.h"
 #include "nvim/pos.h"  // for linenr_T
 #include "nvim/ex_cmds_defs.h"  // for exarg_T
+#include "nvim/screen.h"  // for StlClickRecord
 
 // Values for buflist_getfile()
 enum getf_values {
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index e4e7b63fe3..6c471ab770 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -10930,6 +10930,7 @@ static void f_has(typval_T *argvars, typval_T *rettv)
 #if !defined(UNIX)
     "system",  // TODO(SplinterOfChaos): This IS defined for UNIX!
 #endif
+    "tablineat",
     "tag_binary",
     "tag_old_static",
     "termresponse",
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index b45f13de4c..697a4a765a 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -159,15 +159,6 @@ EXTERN int Screen_mco INIT(= 0);                /* value of p_mco used when
  * These are single-width. */
 EXTERN schar_T  *ScreenLines2 INIT(= NULL);
 
-/*
- * Indexes for tab page line:
- *	N > 0 for label of tab page N
- *	N == 0 for no label
- *	N < 0 for closing tab page -N
- *	N == -999 for closing current tab page
- */
-EXTERN short    *TabPageIdxs INIT(= NULL);
-
 EXTERN int screen_Rows INIT(= 0);           /* actual size of ScreenLines[] */
 EXTERN int screen_Columns INIT(= 0);        /* actual size of ScreenLines[] */
 
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index cb3fc98dfa..9a9cf50e48 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -2347,8 +2347,9 @@ do_mouse (
   if (mouse_row == 0 && firstwin->w_winrow > 0) {
     if (is_drag) {
       if (in_tab_line) {
-        c1 = TabPageIdxs[mouse_col];
-        tabpage_move(c1 <= 0 ? 9999 : c1 - 1);
+        tabpage_move(tab_page_click_defs[mouse_col].type == kStlClickTabClose
+                     ? 9999
+                     : tab_page_click_defs[mouse_col].tabnr - 1);
       }
       return false;
     }
@@ -2358,41 +2359,114 @@ do_mouse (
         && cmdwin_type == 0
         && mouse_col < Columns) {
       in_tab_line = true;
-      c1 = TabPageIdxs[mouse_col];
-      if (c1 >= 0) {
-        if ((mod_mask & MOD_MASK_MULTI_CLICK) == MOD_MASK_2CLICK) {
-          /* double click opens new page */
-          end_visual_mode();
-          tabpage_new();
-          tabpage_move(c1 == 0 ? 9999 : c1 - 1);
-        } else {
-          /* Go to specified tab page, or next one if not clicking
-           * on a label. */
-          goto_tabpage(c1);
-
-          /* It's like clicking on the status line of a window. */
-          if (curwin != old_curwin)
+      c1 = tab_page_click_defs[mouse_col].tabnr;
+      switch (tab_page_click_defs[mouse_col].type) {
+        case kStlClickDisabled: {
+          break;
+        }
+        case kStlClickTabClose: {
+          tabpage_T *tp;
+
+          // Close the current or specified tab page.
+          if (c1 == 999) {
+            tp = curtab;
+          } else {
+            tp = find_tabpage(c1);
+          }
+          if (tp == curtab) {
+            if (first_tabpage->tp_next != NULL) {
+              tabpage_close(false);
+            }
+          } else if (tp != NULL) {
+            tabpage_close_other(tp, false);
+          }
+          break;
+        }
+        case kStlClickTabSwitch: {
+          if ((mod_mask & MOD_MASK_MULTI_CLICK) == MOD_MASK_2CLICK) {
+            // double click opens new page
             end_visual_mode();
+            tabpage_new();
+            tabpage_move(c1 == 0 ? 9999 : c1 - 1);
+          } else {
+            // Go to specified tab page, or next one if not clicking
+            // on a label.
+            goto_tabpage(c1);
+
+            // It's like clicking on the status line of a window.
+            if (curwin != old_curwin) {
+              end_visual_mode();
+            }
+          }
+          break;
+        }
+        case kStlClickFuncRun: {
+          typval_T argv[] = {
+            {
+              .v_lock = VAR_FIXED,
+              .v_type = VAR_NUMBER,
+              .vval = {
+                .v_number = (varnumber_T) tab_page_click_defs[mouse_col].tabnr
+              },
+            },
+            {
+              .v_lock = VAR_FIXED,
+              .v_type = VAR_NUMBER,
+              .vval = {
+                .v_number = (((mod_mask & MOD_MASK_MULTI_CLICK)
+                              == MOD_MASK_4CLICK)
+                             ? 4
+                             : ((mod_mask & MOD_MASK_MULTI_CLICK)
+                                == MOD_MASK_3CLICK)
+                             ? 3
+                             : ((mod_mask & MOD_MASK_MULTI_CLICK)
+                                == MOD_MASK_2CLICK)
+                             ? 2
+                             : 1)
+              },
+            },
+            {
+              .v_lock = VAR_FIXED,
+              .v_type = VAR_STRING,
+              .vval = { .v_string = (char_u *) (which_button == MOUSE_LEFT
+                                                ? "l"
+                                                : which_button == MOUSE_RIGHT
+                                                ? "r"
+                                                : which_button == MOUSE_MIDDLE
+                                                ? "m"
+                                                : "?") },
+            },
+            {
+              .v_lock = VAR_FIXED,
+              .v_type = VAR_STRING,
+              .vval = {
+                .v_string = (char_u[]) {
+                  (char_u) (mod_mask & MOD_MASK_SHIFT ? 's' : ' '),
+                  (char_u) (mod_mask & MOD_MASK_CTRL ? 'c' : ' '),
+                  (char_u) (mod_mask & MOD_MASK_ALT ? 'a' : ' '),
+                  (char_u) (mod_mask & MOD_MASK_META ? 'm' : ' '),
+                  NUL
+                }
+              },
+            }
+          };
+          typval_T rettv;
+          int doesrange;
+          (void) call_func((char_u *) tab_page_click_defs[mouse_col].func,
+                           (int) strlen(tab_page_click_defs[mouse_col].func),
+                           &rettv, ARRAY_SIZE(argv), argv,
+                           curwin->w_cursor.lnum, curwin->w_cursor.lnum,
+                           &doesrange, true, NULL);
+          clear_tv(&rettv);
+          break;
         }
-      } else if (c1 < 0) {
-        tabpage_T       *tp;
-
-        /* Close the current or specified tab page. */
-        if (c1 == -999)
-          tp = curtab;
-        else
-          tp = find_tabpage(-c1);
-        if (tp == curtab) {
-          if (first_tabpage->tp_next != NULL)
-            tabpage_close(false);
-        } else if (tp != NULL)
-          tabpage_close_other(tp, false);
       }
     }
     return true;
   } else if (is_drag && in_tab_line) {
-    c1 = TabPageIdxs[mouse_col];
-    tabpage_move(c1 <= 0 ? 9999 : c1 - 1);
+    tabpage_move(tab_page_click_defs[mouse_col].type == kStlClickTabClose
+                 ? 9999
+                 : tab_page_click_defs[mouse_col].tabnr - 1);
     in_tab_line = false;
     return false;
   }
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index 7a837de45c..11b5e31f77 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -209,44 +209,58 @@
 #define COM_ALL         "nbsmexflrO"    /* all flags for 'comments' option */
 #define COM_MAX_LEN     50              /* maximum length of a part */
 
-/* flags for 'statusline' option */
-#define STL_FILEPATH    'f'             /* path of file in buffer */
-#define STL_FULLPATH    'F'             /* full path of file in buffer */
-#define STL_FILENAME    't'             /* last part (tail) of file path */
-#define STL_COLUMN      'c'             /* column og cursor*/
-#define STL_VIRTCOL     'v'             /* virtual column */
-#define STL_VIRTCOL_ALT 'V'             /* - with 'if different' display */
-#define STL_LINE        'l'             /* line number of cursor */
-#define STL_NUMLINES    'L'             /* number of lines in buffer */
-#define STL_BUFNO       'n'             /* current buffer number */
-#define STL_KEYMAP      'k'             /* 'keymap' when active */
-#define STL_OFFSET      'o'             /* offset of character under cursor*/
-#define STL_OFFSET_X    'O'             /* - in hexadecimal */
-#define STL_BYTEVAL     'b'             /* byte value of character */
-#define STL_BYTEVAL_X   'B'             /* - in hexadecimal */
-#define STL_ROFLAG      'r'             /* readonly flag */
-#define STL_ROFLAG_ALT  'R'             /* - other display */
-#define STL_HELPFLAG    'h'             /* window is showing a help file */
-#define STL_HELPFLAG_ALT 'H'            /* - other display */
-#define STL_FILETYPE    'y'             /* 'filetype' */
-#define STL_FILETYPE_ALT 'Y'            /* - other display */
-#define STL_PREVIEWFLAG 'w'             /* window is showing the preview buf */
-#define STL_PREVIEWFLAG_ALT 'W'         /* - other display */
-#define STL_MODIFIED    'm'             /* modified flag */
-#define STL_MODIFIED_ALT 'M'            /* - other display */
-#define STL_QUICKFIX    'q'             /* quickfix window description */
-#define STL_PERCENTAGE  'p'             /* percentage through file */
-#define STL_ALTPERCENT  'P'             /* percentage as TOP BOT ALL or NN% */
-#define STL_ARGLISTSTAT 'a'             /* argument list status as (x of y) */
-#define STL_PAGENUM     'N'             /* page number (when printing)*/
-#define STL_VIM_EXPR    '{'             /* start of expression to substitute */
-#define STL_MIDDLEMARK  '='             /* separation between left and right */
-#define STL_TRUNCMARK   '<'             /* truncation mark if line is too long*/
-#define STL_USER_HL     '*'             /* highlight from (User)1..9 or 0 */
-#define STL_HIGHLIGHT   '#'             /* highlight name */
-#define STL_TABPAGENR   'T'             /* tab page label nr */
-#define STL_TABCLOSENR  'X'             /* tab page close nr */
-#define STL_ALL         ((char_u *) "fFtcvVlLknoObBrRhHmYyWwMqpPaN{#")
+/// 'statusline' option flags
+enum {
+  STL_FILEPATH        = 'f',  ///< Path of file in buffer.
+  STL_FULLPATH        = 'F',  ///< Full path of file in buffer.
+  STL_FILENAME        = 't',  ///< Last part (tail) of file path.
+  STL_COLUMN          = 'c',  ///< Column og cursor.
+  STL_VIRTCOL         = 'v',  ///< Virtual column.
+  STL_VIRTCOL_ALT     = 'V',  ///< - with 'if different' display.
+  STL_LINE            = 'l',  ///< Line number of cursor.
+  STL_NUMLINES        = 'L',  ///< Number of lines in buffer.
+  STL_BUFNO           = 'n',  ///< Current buffer number.
+  STL_KEYMAP          = 'k',  ///< 'keymap' when active.
+  STL_OFFSET          = 'o',  ///< Offset of character under cursor.
+  STL_OFFSET_X        = 'O',  ///< - in hexadecimal.
+  STL_BYTEVAL         = 'b',  ///< Byte value of character.
+  STL_BYTEVAL_X       = 'B',  ///< - in hexadecimal.
+  STL_ROFLAG          = 'r',  ///< Readonly flag.
+  STL_ROFLAG_ALT      = 'R',  ///< - other display.
+  STL_HELPFLAG        = 'h',  ///< Window is showing a help file.
+  STL_HELPFLAG_ALT    = 'H',  ///< - other display.
+  STL_FILETYPE        = 'y',  ///< 'filetype'.
+  STL_FILETYPE_ALT    = 'Y',  ///< - other display.
+  STL_PREVIEWFLAG     = 'w',  ///< Window is showing the preview buf.
+  STL_PREVIEWFLAG_ALT = 'W',  ///< - other display.
+  STL_MODIFIED        = 'm',  ///< Modified flag.
+  STL_MODIFIED_ALT    = 'M',  ///< - other display.
+  STL_QUICKFIX        = 'q',  ///< Quickfix window description.
+  STL_PERCENTAGE      = 'p',  ///< Percentage through file.
+  STL_ALTPERCENT      = 'P',  ///< Percentage as TOP BOT ALL or NN%.
+  STL_ARGLISTSTAT     = 'a',  ///< Argument list status as (x of y).
+  STL_PAGENUM         = 'N',  ///< Page number (when printing).
+  STL_VIM_EXPR        = '{',  ///< Start of expression to substitute.
+  STL_MIDDLEMARK      = '=',  ///< Separation between left and right.
+  STL_TRUNCMARK       = '<',  ///< Truncation mark if line is too long.
+  STL_USER_HL         = '*',  ///< Highlight from (User)1..9 or 0.
+  STL_HIGHLIGHT       = '#',  ///< Highlight name.
+  STL_TABPAGENR       = 'T',  ///< Tab page label nr.
+  STL_TABCLOSENR      = 'X',  ///< Tab page close nr.
+  STL_CLICK_FUNC      = '@',  ///< Click region start.
+};
+/// C string containing all 'statusline' option flags
+#define STL_ALL ((char_u[]) { \
+  STL_FILEPATH, STL_FULLPATH, STL_FILENAME, STL_COLUMN, STL_VIRTCOL, \
+  STL_VIRTCOL_ALT, STL_LINE, STL_NUMLINES, STL_BUFNO, STL_KEYMAP, STL_OFFSET, \
+  STL_OFFSET_X, STL_BYTEVAL, STL_BYTEVAL_X, STL_ROFLAG, STL_ROFLAG_ALT, \
+  STL_HELPFLAG, STL_HELPFLAG_ALT, STL_FILETYPE, STL_FILETYPE_ALT, \
+  STL_PREVIEWFLAG, STL_PREVIEWFLAG_ALT, STL_MODIFIED, STL_MODIFIED_ALT, \
+  STL_QUICKFIX, STL_PERCENTAGE, STL_ALTPERCENT, STL_ARGLISTSTAT, STL_PAGENUM, \
+  STL_VIM_EXPR, STL_MIDDLEMARK, STL_TRUNCMARK, STL_USER_HL, STL_HIGHLIGHT, \
+  STL_TABPAGENR, STL_TABCLOSENR, STL_CLICK_FUNC, \
+  0, \
+})
 
 /* flags used for parsed 'wildmode' */
 #define WIM_FULL        1
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 43bc2c1f68..be8307e8b3 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -147,6 +147,9 @@ static foldinfo_T win_foldinfo; /* info for 'foldcolumn' */
  */
 static schar_T  *current_ScreenLine;
 
+StlClickDefinition *tab_page_click_defs = NULL;
+long tab_page_click_defs_size = 0;
+
 # define SCREEN_LINE(r, o, e, c, rl)    screen_line((r), (o), (e), (c), (rl))
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "screen.c.generated.h"
@@ -5009,8 +5012,8 @@ win_redr_custom (
   char_u      *stl;
   char_u      *p;
   struct      stl_hlrec hltab[STL_MAX_ITEM];
-  struct      stl_hlrec tabtab[STL_MAX_ITEM];
-  int use_sandbox = FALSE;
+  StlClickRecord tabtab[STL_MAX_ITEM];
+  int use_sandbox = false;
   win_T       *ewp;
   int p_crb_save;
 
@@ -5126,20 +5129,24 @@ win_redr_custom (
   screen_puts(p >= buf + len ? (char_u *)"" : p, row, col, curattr);
 
   if (wp == NULL) {
-    /* Fill the TabPageIdxs[] array for clicking in the tab pagesline. */
+    // Fill the tab_page_click_defs array for clicking in the tab pages line.
     col = 0;
     len = 0;
     p = buf;
-    fillchar = 0;
+    StlClickDefinition cur_click_def = {
+      .type = kStlClickDisabled,
+    };
     for (n = 0; tabtab[n].start != NULL; n++) {
-      len += vim_strnsize(p, (int)(tabtab[n].start - p));
-      while (col < len)
-        TabPageIdxs[col++] = fillchar;
-      p = tabtab[n].start;
-      fillchar = tabtab[n].userhl;
+      len += vim_strnsize(p, (int)(tabtab[n].start - (char *) p));
+      while (col < len) {
+        tab_page_click_defs[col++] = cur_click_def;
+      }
+      p = (char_u *) tabtab[n].start;
+      cur_click_def = tabtab[n].def;
+    }
+    while (col < Columns) {
+      tab_page_click_defs[col++] = cur_click_def;
     }
-    while (col < Columns)
-      TabPageIdxs[col++] = fillchar;
   }
 
 theend:
@@ -5958,9 +5965,9 @@ void screenalloc(bool doclear)
   sattr_T         *new_ScreenAttrs;
   unsigned        *new_LineOffset;
   char_u          *new_LineWraps;
-  short           *new_TabPageIdxs;
-  static int entered = FALSE;                   /* avoid recursiveness */
-  static int done_outofmem_msg = FALSE;         /* did outofmem message */
+  StlClickDefinition *new_tab_page_click_defs;
+  static bool entered = false;  // avoid recursiveness
+  static bool done_outofmem_msg = false;
   int retry_count = 0;
   const bool l_enc_utf8 = enc_utf8;
   const int l_enc_dbcs = enc_dbcs;
@@ -6033,7 +6040,8 @@ retry:
   new_ScreenAttrs = xmalloc((size_t)((Rows + 1) * Columns * sizeof(sattr_T)));
   new_LineOffset = xmalloc((size_t)(Rows * sizeof(unsigned)));
   new_LineWraps = xmalloc((size_t)(Rows * sizeof(char_u)));
-  new_TabPageIdxs = xmalloc((size_t)(Columns * sizeof(short)));
+  new_tab_page_click_defs = xcalloc(
+      (size_t) Columns, sizeof(*new_tab_page_click_defs));
 
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     win_alloc_lines(wp);
@@ -6051,7 +6059,7 @@ retry:
       || new_ScreenAttrs == NULL
       || new_LineOffset == NULL
       || new_LineWraps == NULL
-      || new_TabPageIdxs == NULL
+      || new_tab_page_click_defs == NULL
       || outofmem) {
     if (ScreenLines != NULL || !done_outofmem_msg) {
       /* guess the size */
@@ -6077,8 +6085,8 @@ retry:
     new_LineOffset = NULL;
     xfree(new_LineWraps);
     new_LineWraps = NULL;
-    xfree(new_TabPageIdxs);
-    new_TabPageIdxs = NULL;
+    xfree(new_tab_page_click_defs);
+    new_tab_page_click_defs = NULL;
   } else {
     done_outofmem_msg = FALSE;
 
@@ -6157,7 +6165,8 @@ retry:
   ScreenAttrs = new_ScreenAttrs;
   LineOffset = new_LineOffset;
   LineWraps = new_LineWraps;
-  TabPageIdxs = new_TabPageIdxs;
+  tab_page_click_defs = new_tab_page_click_defs;
+  tab_page_click_defs_size = Columns;
 
   /* It's important that screen_Rows and screen_Columns reflect the actual
    * size of ScreenLines[].  Set them before calling anything. */
@@ -6196,7 +6205,25 @@ void free_screenlines(void)
   xfree(ScreenAttrs);
   xfree(LineOffset);
   xfree(LineWraps);
-  xfree(TabPageIdxs);
+  clear_tab_page_click_defs(tab_page_click_defs, tab_page_click_defs_size);
+  xfree(tab_page_click_defs);
+}
+
+/// Clear tab_page_click_defs table
+///
+/// @param[out]  tpcd  Table to clear.
+/// @param[in]  tpcd_size  Size of the table.
+void clear_tab_page_click_defs(StlClickDefinition *const tpcd,
+                               const long tpcd_size)
+{
+  if (tpcd != NULL) {
+    for (long i = 0; i < tpcd_size; i++) {
+      if (i == 0 || tpcd[i].func != tpcd[i - 1].func) {
+        xfree(tpcd[i].func);
+      }
+    }
+  }
+  memset(tpcd, 0, (size_t) tpcd_size * sizeof(tpcd[0]));
 }
 
 void screenclear(void)
@@ -6804,9 +6831,9 @@ static void draw_tabline(void)
     return;
 
 
-  /* Init TabPageIdxs[] to zero: Clicking outside of tabs has no effect. */
-  for (scol = 0; scol < Columns; ++scol)
-    TabPageIdxs[scol] = 0;
+  // Init TabPageIdxs[] to zero: Clicking outside of tabs has no effect.
+  assert(Columns == tab_page_click_defs_size);
+  clear_tab_page_click_defs(tab_page_click_defs, tab_page_click_defs_size);
 
   /* Use the 'tabline' option if it's set. */
   if (*p_tal != NUL) {
@@ -6904,11 +6931,16 @@ static void draw_tabline(void)
       }
       screen_putchar(' ', 0, col++, attr);
 
-      /* Store the tab page number in TabPageIdxs[], so that
-       * jump_to_mouse() knows where each one is. */
-      ++tabcount;
-      while (scol < col)
-        TabPageIdxs[scol++] = tabcount;
+      // Store the tab page number in tab_page_click_defs[], so that
+      // jump_to_mouse() knows where each one is.
+      tabcount++;
+      while (scol < col) {
+        tab_page_click_defs[scol++] = (StlClickDefinition) {
+          .type = kStlClickTabSwitch,
+          .tabnr = tabcount,
+          .func = NULL,
+        };
+      }
     }
 
     if (use_sep_chars)
@@ -6920,7 +6952,11 @@ static void draw_tabline(void)
     /* Put an "X" for closing the current tab if there are several. */
     if (first_tabpage->tp_next != NULL) {
       screen_putchar('X', 0, (int)Columns - 1, attr_nosel);
-      TabPageIdxs[Columns - 1] = -999;
+      tab_page_click_defs[Columns - 1] = (StlClickDefinition) {
+        .type = kStlClickTabClose,
+        .tabnr = 999,
+        .func = NULL,
+      };
     }
   }
 
diff --git a/src/nvim/screen.h b/src/nvim/screen.h
index debf86ae67..81a8b9ed4c 100644
--- a/src/nvim/screen.h
+++ b/src/nvim/screen.h
@@ -16,6 +16,29 @@
 #define NOT_VALID               40  /* buffer needs complete redraw */
 #define CLEAR                   50  /* screen messed up, clear it */
 
+/// Status line click definition
+typedef struct {
+  enum {
+    kStlClickDisabled = 0,  ///< Clicks to this area are ignored.
+    kStlClickTabSwitch,     ///< Switch to the given tab.
+    kStlClickTabClose,      ///< Close given tab.
+    kStlClickFuncRun,       ///< Run user function.
+  } type;      ///< Type of the click.
+  int tabnr;   ///< Tab page number.
+  char *func;  ///< Function to run.
+} StlClickDefinition;
+
+/// Used for tabline clicks
+typedef struct {
+  StlClickDefinition def;  ///< Click definition.
+  const char *start;       ///< Location where region starts.
+} StlClickRecord;
+
+/// Array defining what should be done when tabline is clicked
+extern StlClickDefinition *tab_page_click_defs;
+
+/// Size of the tab_page_click_defs array
+extern long tab_page_click_defs_size;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "screen.h.generated.h"
diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index b3992c4a89..da9d6a0cd2 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -1,7 +1,8 @@
 local helpers = require('test.functional.helpers')
 local Screen = require('test.functional.ui.screen')
-local clear, feed, nvim = helpers.clear, helpers.feed, helpers.nvim
+local clear, feed, meths = helpers.clear, helpers.feed, helpers.meths
 local insert, execute = helpers.insert, helpers.execute
+local eq, funcs = helpers.eq, helpers.funcs
 
 describe('Mouse input', function()
   local screen
@@ -13,11 +14,11 @@ describe('Mouse input', function()
 
   before_each(function()
     clear()
-    nvim('set_option', 'mouse', 'a')
-    nvim('set_option', 'listchars', 'eol:$')
+    meths.set_option('mouse', 'a')
+    meths.set_option('listchars', 'eol:$')
     -- set mouset to very high value to ensure that even in valgrind/travis,
     -- nvim will still pick multiple clicks
-    nvim('set_option', 'mouset', 5000)
+    meths.set_option('mouset', 5000)
     screen = Screen.new(25, 5)
     screen:attach()
     screen:set_default_attr_ids({
@@ -58,31 +59,149 @@ describe('Mouse input', function()
     ]])
   end)
 
-  it('left click in tabline switches to tab', function()
+  describe('tabline', function()
     local tab_attrs = {
       tab  = { background=Screen.colors.LightGrey, underline=true },
       sel  = { bold=true },
       fill = { reverse=true }
     }
-    execute('%delete')
-    insert('this is foo')
-    execute('silent file foo | tabnew | file bar')
-    insert('this is bar')
-    screen:expect([[
-      {tab: + foo }{sel: + bar }{fill:          }{tab:X}|
-      this is ba^r              |
-      ~                        |
-      ~                        |
-                               |
-    ]], tab_attrs)
-    feed('<LeftMouse><4,0>')
-    screen:expect([[
-      {sel: + foo }{tab: + bar }{fill:          }{tab:X}|
-      this is fo^o              |
-      ~                        |
-      ~                        |
-                               |
-    ]], tab_attrs)
+
+    it('left click in default tabline (position 4) switches to tab', function()
+      execute('%delete')
+      insert('this is foo')
+      execute('silent file foo | tabnew | file bar')
+      insert('this is bar')
+      screen:expect([[
+        {tab: + foo }{sel: + bar }{fill:          }{tab:X}|
+        this is ba^r              |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+      feed('<LeftMouse><4,0>')
+      screen:expect([[
+        {sel: + foo }{tab: + bar }{fill:          }{tab:X}|
+        this is fo^o              |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+    end)
+
+    it('left click in default tabline (position 24) closes tab', function()
+      meths.set_option('hidden', true)
+      execute('%delete')
+      insert('this is foo')
+      execute('silent file foo | tabnew | file bar')
+      insert('this is bar')
+      screen:expect([[
+        {tab: + foo }{sel: + bar }{fill:          }{tab:X}|
+        this is ba^r              |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+      feed('<LeftMouse><24,0>')
+      screen:expect([[
+        this is fo^o              |
+        ~                        |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+    end)
+
+    it('double click in default tabline (position 4) opens new tab', function()
+      meths.set_option('hidden', true)
+      execute('%delete')
+      insert('this is foo')
+      execute('silent file foo | tabnew | file bar')
+      insert('this is bar')
+      screen:expect([[
+        {tab: + foo }{sel: + bar }{fill:          }{tab:X}|
+        this is ba^r              |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+      feed('<2-LeftMouse><4,0>')
+      screen:expect([[
+        {sel:  Name] }{tab: + foo  + bar }{fill:  }{tab:X}|
+        ^                         |
+        ~                        |
+        ~                        |
+                                 |
+      ]], tab_attrs)
+    end)
+
+    describe('%@ label', function()
+      before_each(function()
+        execute([[
+          function Test(...)
+            let g:reply = a:000
+            return copy(a:000)  " Check for memory leaks: return should be freed
+          endfunction
+        ]])
+        execute([[
+          function Test2(...)
+            return call('Test', a:000 + [2])
+          endfunction
+        ]])
+        meths.set_option('tabline', '%@Test@test%X-%5@Test2@test2')
+        meths.set_option('showtabline', 2)
+        screen:expect([[
+          {fill:test-test2               }|
+          mouse                    |
+          support and selectio^n    |
+          ~                        |
+                                   |
+        ]], tab_attrs)
+        meths.set_var('reply', {})
+      end)
+
+      local check_reply = function(expected)
+        eq(expected, meths.get_var('reply'))
+        meths.set_var('reply', {})
+      end
+
+      local test_click = function(name, click_str, click_num, mouse_button,
+                                  modifiers)
+        it(name .. ' works', function()
+          eq(1, funcs.has('tablineat'))
+          feed(click_str .. '<3,0>')
+          check_reply({0, click_num, mouse_button, modifiers})
+          feed(click_str .. '<4,0>')
+          check_reply({})
+          feed(click_str .. '<6,0>')
+          check_reply({5, click_num, mouse_button, modifiers, 2})
+          feed(click_str .. '<13,0>')
+          check_reply({5, click_num, mouse_button, modifiers, 2})
+        end)
+      end
+
+      test_click('single left click', '<LeftMouse>', 1, 'l', '    ')
+      test_click('shifted single left click', '<S-LeftMouse>', 1, 'l', 's   ')
+      test_click('shifted single left click with alt modifier',
+                 '<S-A-LeftMouse>', 1, 'l', 's a ')
+      test_click('shifted single left click with alt and ctrl modifiers',
+                 '<S-C-A-LeftMouse>', 1, 'l', 'sca ')
+      -- <C-RightMouse> does not work
+      test_click('shifted single right click with alt modifier',
+                 '<S-A-RightMouse>', 1, 'r', 's a ')
+      -- Modifiers do not work with MiddleMouse
+      test_click('shifted single middle click with alt and ctrl modifiers',
+                 '<MiddleMouse>', 1, 'm', '    ')
+      -- Modifiers do not work with N-*Mouse
+      test_click('double left click', '<2-LeftMouse>', 2, 'l', '    ')
+      test_click('triple left click', '<3-LeftMouse>', 3, 'l', '    ')
+      test_click('quadruple left click', '<4-LeftMouse>', 4, 'l', '    ')
+      test_click('double right click', '<2-RightMouse>', 2, 'r', '    ')
+      test_click('triple right click', '<3-RightMouse>', 3, 'r', '    ')
+      test_click('quadruple right click', '<4-RightMouse>', 4, 'r', '    ')
+      test_click('double middle click', '<2-MiddleMouse>', 2, 'm', '    ')
+      test_click('triple middle click', '<3-MiddleMouse>', 3, 'm', '    ')
+      test_click('quadruple middle click', '<4-MiddleMouse>', 4, 'm', '    ')
+    end)
   end)
 
   it('left drag changes visual selection', function()
@@ -211,7 +330,7 @@ describe('Mouse input', function()
   end)
 
   it('ctrl + left click will search for a tag', function()
-    nvim('set_option', 'tags', './non-existent-tags-file')
+    meths.set_option('tags', './non-existent-tags-file')
     feed('<C-LeftMouse><0,0>')
     screen:expect([[
       E433: No tags file       |