vim-patch:8.0.1309: cannot use 'balloonexpr' in a terminal

Problem:    Cannot use 'balloonexpr' in a terminal.
Solution:   Add 'balloonevalterm' and add code to handle mouse movements in a
            terminal. Initial implementation for Unix with GUI.
https://github.com/vim/vim/commit/51b0f3701ecb440aa72ab6017c1df6940c0e0f6f

8 files changed, 20 insertions, 6 deletions

diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 999cc74185..56b563cba0 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -992,6 +992,7 @@ static int insert_handle_key(InsertState *s)
   case K_LEFTDRAG:
   case K_LEFTRELEASE:
   case K_LEFTRELEASE_NM:
+  case K_MOUSEMOVE:
   case K_MIDDLEMOUSE:
   case K_MIDDLEDRAG:
   case K_MIDDLERELEASE:
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 7159b27665..53571ec8da 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -1953,6 +1953,7 @@ static int command_line_handle_key(CommandLineState *s)
   case K_X2MOUSE:
   case K_X2DRAG:
   case K_X2RELEASE:
+  case K_MOUSEMOVE:
     return command_line_not_changed(s);
 
 
diff --git a/src/nvim/keymap.c b/src/nvim/keymap.c
index 517274a1d3..fbc1bf1122 100644
--- a/src/nvim/keymap.c
+++ b/src/nvim/keymap.c
@@ -288,6 +288,7 @@ static const struct key_name_entry {
   { K_LEFTDRAG,        "LeftDrag" },
   { K_LEFTRELEASE,     "LeftRelease" },
   { K_LEFTRELEASE_NM,  "LeftReleaseNM" },
+  { K_MOUSEMOVE,       "MouseMove" },
   { K_MIDDLEMOUSE,     "MiddleMouse" },
   { K_MIDDLEDRAG,      "MiddleDrag" },
   { K_MIDDLERELEASE,   "MiddleRelease" },
@@ -338,9 +339,9 @@ static struct mousetable {
   {(int)KE_X2MOUSE,           MOUSE_X2,       TRUE,   FALSE},
   {(int)KE_X2DRAG,            MOUSE_X2,       FALSE,  TRUE},
   {(int)KE_X2RELEASE,         MOUSE_X2,       FALSE,  FALSE},
-  /* DRAG without CLICK */
-  {(int)KE_IGNORE,            MOUSE_RELEASE,  FALSE,  TRUE},
-  /* RELEASE without CLICK */
+  // DRAG without CLICK
+  {(int)K_MOUSEMOVE,          MOUSE_RELEASE,  FALSE,  TRUE},
+  // RELEASE without CLICK
   {(int)KE_IGNORE,            MOUSE_RELEASE,  FALSE,  FALSE},
   {0,                         0,              0,      0},
 };
diff --git a/src/nvim/keymap.h b/src/nvim/keymap.h
index ada9bc5780..d31196d412 100644
--- a/src/nvim/keymap.h
+++ b/src/nvim/keymap.h
@@ -242,7 +242,7 @@ enum key_extra {
   , KE_NOP = 97               // no-op: does nothing
   // , KE_FOCUSGAINED = 98    // focus gained
   // , KE_FOCUSLOST = 99      // focus lost
-  // , KE_MOUSEMOVE = 100     // mouse moved with no button down
+  , KE_MOUSEMOVE = 100        // mouse moved with no button down
   // , KE_CANCEL = 101        // return from vgetc
   , KE_EVENT = 102            // event
   , KE_COMMAND = 104          // <Cmd> special key
@@ -411,6 +411,7 @@ enum key_extra {
 #define K_LEFTDRAG      TERMCAP2KEY(KS_EXTRA, KE_LEFTDRAG)
 #define K_LEFTRELEASE   TERMCAP2KEY(KS_EXTRA, KE_LEFTRELEASE)
 #define K_LEFTRELEASE_NM TERMCAP2KEY(KS_EXTRA, KE_LEFTRELEASE_NM)
+#define K_MOUSEMOVE     TERMCAP2KEY(KS_EXTRA, KE_MOUSEMOVE)
 #define K_MIDDLEMOUSE   TERMCAP2KEY(KS_EXTRA, KE_MIDDLEMOUSE)
 #define K_MIDDLEDRAG    TERMCAP2KEY(KS_EXTRA, KE_MIDDLEDRAG)
 #define K_MIDDLERELEASE TERMCAP2KEY(KS_EXTRA, KE_MIDDLERELEASE)
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 1783f62247..c3815588a6 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -1193,7 +1193,8 @@ void wait_return(int redraw)
              || c == K_MIDDLEDRAG || c == K_MIDDLERELEASE
              || c == K_RIGHTDRAG  || c == K_RIGHTRELEASE
              || c == K_MOUSELEFT  || c == K_MOUSERIGHT
-             || c == K_MOUSEDOWN  || c == K_MOUSEUP);
+             || c == K_MOUSEDOWN  || c == K_MOUSEUP
+             || c == K_MOUSEMOVE);
     os_breakcheck();
     /*
      * Avoid that the mouse-up event causes visual mode to start.
diff --git a/src/nvim/misc1.c b/src/nvim/misc1.c
index 34c43da0f7..68a1bba78d 100644
--- a/src/nvim/misc1.c
+++ b/src/nvim/misc1.c
@@ -602,6 +602,7 @@ int is_mouse_key(int c)
          || c == K_LEFTDRAG
          || c == K_LEFTRELEASE
          || c == K_LEFTRELEASE_NM
+         || c == K_MOUSEMOVE
          || c == K_MIDDLEMOUSE
          || c == K_MIDDLEDRAG
          || c == K_MIDDLERELEASE
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index c948881eca..616268fcd1 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -294,6 +294,7 @@ static const struct nv_cmd {
   { K_LEFTDRAG, nv_mouse,      0,                      0 },
   { K_LEFTRELEASE, nv_mouse,   0,                      0 },
   { K_LEFTRELEASE_NM, nv_mouse, 0,                     0 },
+  { K_MOUSEMOVE, nv_mouse,     0,                      0 },
   { K_MIDDLEMOUSE, nv_mouse,   0,                      0 },
   { K_MIDDLEDRAG, nv_mouse,    0,                      0 },
   { K_MIDDLERELEASE, nv_mouse, 0,                      0 },
@@ -2263,6 +2264,10 @@ do_mouse (
     break;
   }
 
+  if (c == K_MOUSEMOVE) {
+    // Mouse moved without a button pressed.
+    return false;
+  }
 
   /*
    * Ignore drag and release events if we didn't get a click.
@@ -3390,7 +3395,7 @@ bool add_to_showcmd(int c)
   static int ignore[] =
   {
     K_IGNORE,
-    K_LEFTMOUSE, K_LEFTDRAG, K_LEFTRELEASE,
+    K_LEFTMOUSE, K_LEFTDRAG, K_LEFTRELEASE, K_MOUSEMOVE,
     K_MIDDLEMOUSE, K_MIDDLEDRAG, K_MIDDLERELEASE,
     K_RIGHTMOUSE, K_RIGHTDRAG, K_RIGHTRELEASE,
     K_MOUSEDOWN, K_MOUSEUP, K_MOUSELEFT, K_MOUSERIGHT,
@@ -7036,6 +7041,7 @@ static void nv_g_cmd(cmdarg_T *cap)
   case K_LEFTMOUSE:
   case K_LEFTDRAG:
   case K_LEFTRELEASE:
+  case K_MOUSEMOVE:
   case K_RIGHTMOUSE:
   case K_RIGHTDRAG:
   case K_RIGHTRELEASE:
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index afad20f557..c07a956dde 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -450,6 +450,7 @@ static int terminal_execute(VimState *state, int key)
     case K_LEFTMOUSE:
     case K_LEFTDRAG:
     case K_LEFTRELEASE:
+    case K_MOUSEMOVE:
     case K_MIDDLEMOUSE:
     case K_MIDDLEDRAG:
     case K_MIDDLERELEASE:
@@ -1098,6 +1099,7 @@ static bool send_mouse_event(Terminal *term, int c)
     switch (c) {
       case K_LEFTDRAG: drag = true;   FALLTHROUGH;
       case K_LEFTMOUSE: button = 1; break;
+      case K_MOUSEMOVE: drag = true; button = 0; break;
       case K_MIDDLEDRAG: drag = true; FALLTHROUGH;
       case K_MIDDLEMOUSE: button = 2; break;
       case K_RIGHTDRAG: drag = true;  FALLTHROUGH;