From 0dcfd0e8d101389fb6a33a7e887114ea0c062648 Mon Sep 17 00:00:00 2001
From: Ville Hakulinen <ville.hakulinen@gmail.com>
Date: Fri, 10 Sep 2021 17:24:41 +0300
Subject: [PATCH] fix(mouse.c): fix mouse drag positions on multigrid #12667

Currently, multigrid mouse drag positions are handled incorrectly if the
drag event is not in the top left grid. Fix this by not adjusting the
position of the event in jump_to_mouse.

related: #15091
---
 src/nvim/mouse.c                      |  4 --
 test/functional/ui/multigrid_spec.lua | 61 +++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index c599f4ea97..c4fa269851 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -228,10 +228,6 @@ retnomove:
       redraw_curbuf_later(INVERTED);            // delete the inversion
     }
 
-
-    row -= curwin->w_winrow;
-    col -= curwin->w_wincol;
-
     // When clicking beyond the end of the window, scroll the screen.
     // Scroll by however many rows outside the window we are.
     if (row < 0) {
diff --git a/test/functional/ui/multigrid_spec.lua b/test/functional/ui/multigrid_spec.lua
index 03cb43a7d1..fdf8e66e4f 100644
--- a/test/functional/ui/multigrid_spec.lua
+++ b/test/functional/ui/multigrid_spec.lua
@@ -34,6 +34,7 @@ describe('ext_multigrid', function()
       [17] = {background = Screen.colors.LightGrey, underline = true, bold = true, foreground = Screen.colors.Magenta},
       [18] = {bold = true, foreground = Screen.colors.Magenta},
       [19] = {foreground = Screen.colors.Brown},
+      [20] = {background = Screen.colors.LightGrey},
     })
   end)
 
@@ -2034,6 +2035,66 @@ describe('ext_multigrid', function()
     ]]}
   end)
 
+  it('supports mouse drag with mouse=a', function()
+    command('set mouse=a')
+    command('vsplit')
+    command('wincmd l')
+    command('split')
+    command('enew')
+    feed('ifoo\nbar<esc>')
+
+    meths.input_mouse('left', 'press', '', 5, 0, 0)
+    poke_eventloop()
+    meths.input_mouse('left', 'drag', '', 5, 1, 2)
+
+    screen:expect{grid=[[
+    ## grid 1
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}[5:--------------------------]|
+      [4:--------------------------]{12:│}{11:[No Name] [+]             }|
+      [4:--------------------------]{12:│}[2:--------------------------]|
+      [4:--------------------------]{12:│}[2:--------------------------]|
+      [4:--------------------------]{12:│}[2:--------------------------]|
+      [4:--------------------------]{12:│}[2:--------------------------]|
+      [4:--------------------------]{12:│}[2:--------------------------]|
+      {12:[No Name]                  [No Name]                 }|
+      [3:-----------------------------------------------------]|
+    ## grid 2
+                                |
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+    ## grid 3
+      {7:-- VISUAL --}                                         |
+    ## grid 4
+                                |
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+    ## grid 5
+      {20:foo}                       |
+      {20:ba}^r                       |
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+      {1:~                         }|
+    ]]}
+
+  end)
+
   it('has viewport information', function()
     screen:try_resize(48, 8)
     screen:expect{grid=[[