Move window resize timeouts into the GTK frontend.

In the changes around commit 420fe75552afa94, I made the terminal
suspend output processing while it waited for a term_size() callback
in response to a resize request. Because on X11 there are unusual
circumstances in which you never receive that callback, I also added a
last-ditch 5-second timeout, so that eventually we'll resume terminal
output processing regardless.

But the timeout lives in terminal.c, in the cross-platform code. This
is pointless on Windows (where resize processing is synchronous, so we
always finish it before the timer code next gets called anyway), but I
decided it was easier to keep the whole mechanism in terminal.c in the
absence of a good reason not to.

Now I've found that reason. We _also_ generate window resizes locally
to the GTK front end, in response to the key combinations that change
the font size, and _those_ still have an asynchrony problem.

So, to begin with, I'm refactoring the request_resize system so that
now there's an explicit callback from the frontend to the terminal to
say 'Your resize request has now been processed, whether or not you've
received a term_size() call'. On Windows, this simplifies matters
greatly because we always know exactly when to call that, and don't
have to keep a 'have we called term_size() already?' flag. On GTK, the
timing complexity previously in terminal.c has moved into window.c.

No functional change (I hope). The payoff will be in the next commit.

2 files changed, 7 insertions, 34 deletions

diff --git a/terminal/terminal.c b/terminal/terminal.c
index ca36e4f9..fbaa619b 100644
--- a/terminal/terminal.c
+++ b/terminal/terminal.c
@@ -1220,12 +1220,6 @@ static void term_timer(void *ctx, unsigned long now)
 
     if (term->window_update_pending)
         term_update_callback(term);
-
-    if (term->win_resize_pending == WIN_RESIZE_AWAIT_REPLY &&
-        now == term->win_resize_timeout) {
-        term->win_resize_pending = WIN_RESIZE_NO;
-        queue_toplevel_callback(term_out_cb, term);
-    }
 }
 
 static void term_update_callback(void *ctx)
@@ -1426,8 +1420,6 @@ void term_update(Terminal *term)
         term->win_resize_pending = WIN_RESIZE_AWAIT_REPLY;
         win_request_resize(term->win, term->win_resize_pending_w,
                            term->win_resize_pending_h);
-        term->win_resize_timeout = schedule_timer(
-            WIN_RESIZE_TIMEOUT, term_timer, term);
     }
     if (term->win_zorder_pending) {
         win_set_zorder(term->win, term->win_zorder_top);
@@ -2151,14 +2143,6 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
     int sblen;
     int save_alt_which = term->alt_which;
 
-    /* If we were holding buffered terminal data because we were
-     * waiting for confirmation of a resize, queue a callback to start
-     * processing it again. */
-    if (term->win_resize_pending == WIN_RESIZE_AWAIT_REPLY) {
-        term->win_resize_pending = WIN_RESIZE_NO;
-        queue_toplevel_callback(term_out_cb, term);
-    }
-
     if (newrows == term->rows && newcols == term->cols &&
         newsavelines == term->savelines)
         return;                        /* nothing to do */
@@ -2336,6 +2320,13 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
         backend_size(term->backend, term->cols, term->rows);
 }
 
+void term_resize_request_completed(Terminal *term)
+{
+    assert(term->win_resize_pending == WIN_RESIZE_AWAIT_REPLY);
+    term->win_resize_pending = WIN_RESIZE_NO;
+    queue_toplevel_callback(term_out_cb, term);
+}
+
 /*
  * Hand a backend to the terminal, so it can be notified of resizes.
  */
diff --git a/terminal/terminal.h b/terminal/terminal.h
index b2347f9a..3f918b22 100644
--- a/terminal/terminal.h
+++ b/terminal/terminal.h
@@ -427,24 +427,6 @@ struct terminal_tag {
         WIN_RESIZE_NO, WIN_RESIZE_NEED_SEND, WIN_RESIZE_AWAIT_REPLY
     } win_resize_pending;
     int win_resize_pending_w, win_resize_pending_h;
-
-    /*
-     * Not every frontend / TermWin implementation can be relied on
-     * 100% to reply to a resize request in a timely manner. (In X11
-     * it's all asynchronous and goes via the window manager, and if
-     * your window manager is seriously unwell, you'd rather not have
-     * terminal windows start becoming unusable as a knock-on effect,
-     * since those are just the thing you might need to use for
-     * emergency WM maintenance!) So when we enter AWAIT_REPLY status,
-     * we also set a 5-second timer, after which we'll regretfully
-     * conclude that a resize is probably not going to happen after
-     * all.
-     *
-     * However, in non-emergency cases, the plan is that this
-     * shouldn't be needed, for one reason or another.
-     */
-    long win_resize_timeout;
-    #define WIN_RESIZE_TIMEOUT (TICKSPERSEC*5)
 };
 
 static inline bool in_utf(Terminal *term)