No mouse release events in terminal mode

[Kavantix]

Neovim version (nvim -v)

NVIM v0.6.0-dev+600-gf71be1f87

Vim (not Nvim) behaves the same?

no, vim 8.2 does send mouse release events

Operating system/version

macOS 11.3.1

Terminal name/version

kitty but tested on many

$TERM environment variable

xterm-kitty but tested on many

Installation

brew neovim-nightly

How to reproduce the issue

1. install go
2. download tcell mouse demo
3. run :set mouse=a
4. open a terminal in nvim using :term
5. run go run mouse.go
6. select an area with the mouse

Expected behavior

After releasing the mouse button the selected area should be green.
In both vim and a plain terminal this behaviour can be observed

Actual behavior

The area only becomes green after triggering some other mouse event (tcell assumes that event is a mouse release)

[Kavantix]

Some extra info can be found in: awesome-gocui/gocui#99

[zeertzjq]

I can reproduce this in both TUI and GUI.

[Kavantix]

Updated the OP indeed I have mouse enabled and yes it also indeed happens in GUI (tried goneovim)

[zeertzjq]

I can also reproduce this when running Nvim inside Nvim terminal.
In outer Nvim:

set mouse=a

In inner Nvim:

set mouse=a
set noshowmode
noremap <LeftRelease> <Cmd>echomsg 'LeftRelease' .. localtime()<CR>

Message doesn't change at the end of mouse drag, only at next mouse event. Even if I press some keys after releasing mouse, message still only changes at next mouse event.

[zeertzjq]

The following diff seems to solve the problem:

diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index 35c68fa1f..a78b10299 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -1211,7 +1211,7 @@ static VTermKey convert_key(int key, VTermModifier *statep)
 
 static void mouse_action(Terminal *term, int button, int row, int col, bool drag, VTermModifier mod)
 {
-  if (term->pressed_button && (term->pressed_button != button || !drag)) {
+  if (button && term->pressed_button && term->pressed_button != button) {
     // release the previous button
     vterm_mouse_button(term->vt, term->pressed_button, 0, mod);
     term->pressed_button = 0;
@@ -1220,10 +1220,11 @@ static void mouse_action(Terminal *term, int button, int row, int col, bool drag
   // move the mouse
   vterm_mouse_move(term->vt, row, col, mod);
 
-  if (!term->pressed_button) {
-    // press the button if not already pressed
-    vterm_mouse_button(term->vt, button, 1, mod);
-    term->pressed_button = button;
+  if (button) {
+    vterm_mouse_button(term->vt, button, drag, mod);
+    if (drag) {
+      term->pressed_button = button;
+    }
   }
 }
 
@@ -1246,23 +1247,26 @@ static bool send_mouse_event(Terminal *term, int c)
 
     switch (c) {
     case K_LEFTDRAG:
-      drag = true;   FALLTHROUGH;
     case K_LEFTMOUSE:
+      drag = true;   FALLTHROUGH;
+    case K_LEFTRELEASE:
       button = 1; break;
     case K_MOUSEMOVE:
-      drag = true; button = 0; break;
+      button = 0; break;
     case K_MIDDLEDRAG:
-      drag = true; FALLTHROUGH;
     case K_MIDDLEMOUSE:
+      drag = true; FALLTHROUGH;
+    case K_MIDDLERELEASE:
       button = 2; break;
     case K_RIGHTDRAG:
-      drag = true;  FALLTHROUGH;
     case K_RIGHTMOUSE:
+      drag = true;  FALLTHROUGH;
+    case K_RIGHTRELEASE:
       button = 3; break;
     case K_MOUSEDOWN:
-      button = 4; break;
+      drag = true; button = 4; break;
     case K_MOUSEUP:
-      button = 5; break;
+      drag = true; button = 5; break;
     default:
       return false;
     }

[zeertzjq]

Or maybe pressed_button should even be removed, as there can be multiple buttons down at the same time (e.g. scrolling while dragging):

diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index 35c68fa1f..9880099a3 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -135,7 +135,6 @@ struct terminal {
     int row, col;
     bool visible;
   } cursor;
-  int pressed_button;               // which mouse button is pressed
   bool pending_resize;              // pending width/height
 
   bool color_set[16];
@@ -1211,19 +1210,9 @@ static VTermKey convert_key(int key, VTermModifier *statep)
 
 static void mouse_action(Terminal *term, int button, int row, int col, bool drag, VTermModifier mod)
 {
-  if (term->pressed_button && (term->pressed_button != button || !drag)) {
-    // release the previous button
-    vterm_mouse_button(term->vt, term->pressed_button, 0, mod);
-    term->pressed_button = 0;
-  }
-
-  // move the mouse
   vterm_mouse_move(term->vt, row, col, mod);
-
-  if (!term->pressed_button) {
-    // press the button if not already pressed
-    vterm_mouse_button(term->vt, button, 1, mod);
-    term->pressed_button = button;
+  if (button) {
+    vterm_mouse_button(term->vt, button, drag, mod);
   }
 }
 
@@ -1246,23 +1235,26 @@ static bool send_mouse_event(Terminal *term, int c)
 
     switch (c) {
     case K_LEFTDRAG:
-      drag = true;   FALLTHROUGH;
     case K_LEFTMOUSE:
+      drag = true;   FALLTHROUGH;
+    case K_LEFTRELEASE:
       button = 1; break;
     case K_MOUSEMOVE:
-      drag = true; button = 0; break;
+      button = 0; break;
     case K_MIDDLEDRAG:
-      drag = true; FALLTHROUGH;
     case K_MIDDLEMOUSE:
+      drag = true; FALLTHROUGH;
+    case K_MIDDLERELEASE:
       button = 2; break;
     case K_RIGHTDRAG:
-      drag = true;  FALLTHROUGH;
     case K_RIGHTMOUSE:
+      drag = true;  FALLTHROUGH;
+    case K_RIGHTRELEASE:
       button = 3; break;
     case K_MOUSEDOWN:
-      button = 4; break;
+      drag = true; button = 4; break;
     case K_MOUSEUP:
-      button = 5; break;
+      drag = true; button = 5; break;
     default:
       return false;
     }