Change mouse cursor on terminal mode change (#865)

Some terminals have functionality around changing the type of mouse
cursor dynamically (arrow and text) based on which mode(s) the VTE is
in. For example, gnome-terminal changes the cursor from text (default)
to an arrow when opening programs that track mouse events (e.g. vim,
emacs, tmux, htop, etc.). The programs all allow using the mouse
interactively under some circumstances (like executing `set mouse=a` in
vim).

The programs that use an interactive mouse set the terminal mode to
different values. Though they're not entirely the same terminal mode
across programs, an emulator like vte (the library gnome-terminal
implements), changes the mouse cursor if the mouse mode is one of the
following:

- 1000: Mouse Click Tracking
- 1001: Mouse Highlight Tracking
- 1002: Mouse Cell Motion Tracking
- 1003: Mouse All Motion Tracking
- 1004: Mouse Focus Tracking

See https://github.com/GNOME/vte/blob/6acfa59dfcceef65c1f7e3570db37ab245f049c4/src/vteseq.cc#L708
for more information.

This commit adds functionality that changes the winit/glutin
`MouseCursor` when a mouse-listening mode of 1000-1004 is set. It
behaves similarly to when the window title changes.

1 files changed, 13 insertions, 4 deletions

diff --git a/src/ansi.rs b/src/ansi.rs
index ec139294..3d66b497 100644
--- a/src/ansi.rs
+++ b/src/ansi.rs
@@ -21,7 +21,7 @@ use vte;
 
 use index::{Column, Line, Contains};
 
-use ::Rgb;
+use ::{MouseCursor, Rgb};
 
 // Parse color arguments
 //
@@ -178,6 +178,9 @@ pub trait Handler {
     /// OSC to set window title
     fn set_title(&mut self, &str) {}
 
+    /// Set the window's mouse cursor
+    fn set_mouse_cursor(&mut self, MouseCursor) {}
+
     /// Set the cursor style
     fn set_cursor_style(&mut self, _: Option<CursorStyle>) {}
 
@@ -402,7 +405,9 @@ pub enum Mode {
     /// ?1000
     ReportMouseClicks = 1000,
     /// ?1002
-    ReportMouseMotion = 1002,
+    ReportCellMouseMotion = 1002,
+    /// ?1003
+    ReportAllMouseMotion = 1003,
     /// ?1004
     ReportFocusInOut = 1004,
     /// ?1006
@@ -427,12 +432,16 @@ impl Mode {
                 12 => Mode::BlinkingCursor,
                 25 => Mode::ShowCursor,
                 1000 => Mode::ReportMouseClicks,
-                1002 => Mode::ReportMouseMotion,
+                1002 => Mode::ReportCellMouseMotion,
+                1003 => Mode::ReportAllMouseMotion,
                 1004 => Mode::ReportFocusInOut,
                 1006 => Mode::SgrMouse,
                 1049 => Mode::SwapScreenAndSetRestoreCursor,
                 2004 => Mode::BracketedPaste,
-                _ => return None
+                _ => {
+                    trace!("[unhandled] mode={:?}", num);
+                    return None
+                }
             })
         } else {
             Some(match num {