Support for windows larger than the client.

This adds two new options, window-size and default-size, and a new
command, resize-window.

The force-width and force-height options, and the session_width and
session_height formats have been removed.

The new window-size option tells tmux how to work out the size of
windows: largest means it picks the size of the largest session,
smallest the smallest session (similar to the old behaviour) and
manual means that it does not automatically resize
windows. aggressive-resize modifies the choice of session for largest
and smallest as it did before.

If a window is in a session attached to a client that is too small,
only part of the window is shown. tmux attempts to keep the cursor
visible, so the part of the window displayed is changed as the cursor
moves (with a small delay, to try and avoid excess redrawing when
applications redraw status lines or similar that are not currently
visible).

Drawing windows which are larger than the client is not as efficient
as those which fit, particularly when the cursor moves, so it is
recommended to avoid using this on slow machines or networks (set
window-size to smallest or manual).

The resize-window command can be used to resize a window manually. If
it is used, the window-size option is automatically set to manual for
the window (undo this with "setw -u window-size"). resize-window works
in a similar way to resize-pane (-U -D -L -R -x -y flags) but also has
-a and -A flags. -a sets the window to the size of the smallest client
(what it would be if window-size was smallest) and -A the largest.

For the same behaviour as force-width or force-height, use
resize-width -x or -y.

If the global window-size option is set to manual, the default-size
option is used for new windows. If -x or -y is used with new-session,
that sets the default-size option for the new session.

The maximum size of a window is 10000x10000. But expect applications
to complain and higher memory use if you make a window that big. The
minimum size is the size required for the current layout including
borders.

This change allows some code improvements, most notably that since
windows can now never be cropped, that code can be removed from the
layout code, and since panes can now never be outside the size of the
window, window_pane_visible can be removed.

29 files changed, 1276 insertions, 569 deletions

diff --git a/Makefile.am b/Makefile.am
index a57baa42..e62a161a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -100,6 +100,7 @@ dist_tmux_SOURCES = \
 	cmd-rename-session.c \
 	cmd-rename-window.c \
 	cmd-resize-pane.c \
+	cmd-resize-window.c \
 	cmd-respawn-pane.c \
 	cmd-respawn-window.c \
 	cmd-rotate-window.c \
diff --git a/TODO b/TODO
index 32afa197..4a92eee9 100644
--- a/TODO
+++ b/TODO
@@ -61,7 +61,6 @@
 	  not attached to a cell at all. this could be the time to introduce
 	  panelink to replace layout_cell
 	* way to set hints/limits about pane size for resizing
-	* panning over window (window larger than visible)
 	* a mode where one application can cross two panes (ie x|y, width =
 	  COLUMNS/2 but height = ROWS * 2)
 	* separate active panes for different clients
@@ -131,3 +130,14 @@
 	* finish hooks for notifys
 	* for session_closed, if no sessions at all, perhaps fake up a
 	  temporary one
+
+- pan
+	* tty_window_offset should try to keep as much as active pane
+	  visible as possible
+	* rather than centering cursor it might be better if only
+	  moved offset when it gets close to an edge?
+	* a way to force offset to a particular part of window, scroll
+	  around the window -- command resize-window -d -l -r -u to
+	  move offset and a flag to go back to tracking - but there
+	  is no per-client window data structure so it will have
+	  to forget when the window is changed
diff --git a/cmd-attach-session.c b/cmd-attach-session.c
index 0db0d855..73ff530d 100644
--- a/cmd-attach-session.c
+++ b/cmd-attach-session.c
@@ -115,6 +115,7 @@ cmd_attach_session(struct cmdq_item *item, const char *tflag, int dflag,
 		c->session = s;
 		if (~item->shared->flags & CMDQ_SHARED_REPEAT)
 			server_client_set_key_table(c, NULL);
+		tty_update_client_offset(c);
 		status_timer_start(c);
 		notify_client("client-session-changed", c);
 		session_update_activity(s, NULL);
@@ -142,6 +143,7 @@ cmd_attach_session(struct cmdq_item *item, const char *tflag, int dflag,
 
 		c->session = s;
 		server_client_set_key_table(c, NULL);
+		tty_update_client_offset(c);
 		status_timer_start(c);
 		notify_client("client-session-changed", c);
 		session_update_activity(s, NULL);
diff --git a/cmd-break-pane.c b/cmd-break-pane.c
index 74ecce6f..3b929dee 100644
--- a/cmd-break-pane.c
+++ b/cmd-break-pane.c
@@ -76,7 +76,7 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 	window_lost_pane(w, wp);
 	layout_close_pane(wp);
 
-	w = wp->window = window_create(dst_s->sx, dst_s->sy);
+	w = wp->window = window_create(w->sx, w->sy);
 	TAILQ_INSERT_HEAD(&w->panes, wp, entry);
 	w->active = wp;
 
diff --git a/cmd-list-sessions.c b/cmd-list-sessions.c
index df8a25bc..72ff47e8 100644
--- a/cmd-list-sessions.c
+++ b/cmd-list-sessions.c
@@ -30,8 +30,7 @@
 
 #define LIST_SESSIONS_TEMPLATE				\
 	"#{session_name}: #{session_windows} windows "	\
-	"(created #{t:session_created}) "		\
-	"[#{session_width}x#{session_height}]"		\
+	"(created #{t:session_created})"		\
 	"#{?session_grouped, (group ,}"			\
 	"#{session_group}#{?session_grouped,),}"	\
 	"#{?session_attached, (attached),}"
diff --git a/cmd-new-session.c b/cmd-new-session.c
index e809de24..162a50bd 100644
--- a/cmd-new-session.c
+++ b/cmd-new-session.c
@@ -71,14 +71,15 @@ cmd_new_session_exec(struct cmd *self, struct cmdq_item *item)
 	struct session		*s, *as, *groupwith;
 	struct window		*w;
 	struct environ		*env;
+	struct options		*oo;
 	struct termios		 tio, *tiop;
 	struct session_group	*sg;
 	const char		*errstr, *template, *group, *prefix;
-	const char		*path, *cmd, *tmp;
+	const char		*path, *cmd, *tmp, *value;
 	char		       **argv, *cause, *cp, *newname, *cwd = NULL;
 	int			 detached, already_attached, idx, argc;
 	int			 is_control = 0;
-	u_int			 sx, sy;
+	u_int			 sx, sy, dsx = 80, dsy = 24;
 	struct environ_entry	*envent;
 	struct cmd_find_state	 fs;
 	enum cmd_retval		 retval;
@@ -189,44 +190,53 @@ cmd_new_session_exec(struct cmd *self, struct cmdq_item *item)
 		}
 	}
 
-	/* Find new session size. */
-	if (!detached) {
-		sx = c->tty.sx;
-		sy = c->tty.sy;
-		if (!is_control &&
-		    sy > 0 &&
-		    options_get_number(global_s_options, "status"))
-			sy--;
-	} else {
-		sx = 80;
-		sy = 24;
-	}
-	if ((is_control || detached) && args_has(args, 'x')) {
+	/* Get default session size. */
+	if (args_has(args, 'x')) {
 		tmp = args_get(args, 'x');
 		if (strcmp(tmp, "-") == 0) {
 			if (c != NULL)
-				sx = c->tty.sx;
+				dsx = c->tty.sx;
 		} else {
-			sx = strtonum(tmp, 1, USHRT_MAX, &errstr);
+			dsx = strtonum(tmp, 1, USHRT_MAX, &errstr);
 			if (errstr != NULL) {
 				cmdq_error(item, "width %s", errstr);
 				goto error;
 			}
 		}
 	}
-	if ((is_control || detached) && args_has(args, 'y')) {
+	if (args_has(args, 'y')) {
 		tmp = args_get(args, 'y');
 		if (strcmp(tmp, "-") == 0) {
 			if (c != NULL)
-				sy = c->tty.sy;
+				dsy = c->tty.sy;
 		} else {
-			sy = strtonum(tmp, 1, USHRT_MAX, &errstr);
+			dsy = strtonum(tmp, 1, USHRT_MAX, &errstr);
 			if (errstr != NULL) {
 				cmdq_error(item, "height %s", errstr);
 				goto error;
 			}
 		}
 	}
+
+	/* Find new session size. */
+	if (!detached && !is_control) {
+		sx = c->tty.sx;
+		sy = c->tty.sy;
+		if (!is_control &&
+		    sy > 0 &&
+		    options_get_number(global_s_options, "status"))
+			sy--;
+	} else {
+		value = options_get_string(global_s_options, "default-size");
+		if (sscanf(value, "%ux%u", &sx, &sy) != 2) {
+			sx = 80;
+			sy = 24;
+		}
+		if (args_has(args, 'x'))
+			sx = dsx;
+		if (args_has(args, 'y'))
+			sy = dsy;
+	}
 	if (sx == 0)
 		sx = 1;
 	if (sy == 0)
@@ -262,10 +272,15 @@ cmd_new_session_exec(struct cmd *self, struct cmdq_item *item)
 	if (c != NULL && !args_has(args, 'E'))
 		environ_update(global_s_options, c->environ, env);
 
+	/* Set up the options. */
+	oo = options_create(global_s_options);
+	if (args_has(args, 'x') || args_has(args, 'y'))
+		options_set_string(oo, "default-size", 0, "%ux%u", dsx, dsy);
+
 	/* Create the new session. */
 	idx = -1 - options_get_number(global_s_options, "base-index");
-	s = session_create(prefix, newname, argc, argv, path, cwd, env, tiop,
-	    idx, sx, sy, &cause);
+	s = session_create(prefix, newname, argc, argv, path, cwd, env, oo,
+	    tiop, idx, &cause);
 	environ_free(env);
 	if (s == NULL) {
 		cmdq_error(item, "create session failed: %s", cause);
@@ -313,6 +328,7 @@ cmd_new_session_exec(struct cmd *self, struct cmdq_item *item)
 		c->session = s;
 		if (~item->shared->flags & CMDQ_SHARED_REPEAT)
 			server_client_set_key_table(c, NULL);
+		tty_update_client_offset(c);
 		status_timer_start(c);
 		notify_client("client-session-changed", c);
 		session_update_activity(s, NULL);
diff --git a/cmd-resize-window.c b/cmd-resize-window.c
new file mode 100644
index 00000000..8c4bc3f6
--- /dev/null
+++ b/cmd-resize-window.c
@@ -0,0 +1,109 @@
+/* $OpenBSD$ */
+
+/*
+ * Copyright (c) 2018 Nicholas Marriott <nicholas.marriott@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <stdlib.h>
+
+#include "tmux.h"
+
+/*
+ * Increase or decrease window size.
+ */
+
+static enum cmd_retval	cmd_resize_window_exec(struct cmd *,
+			    struct cmdq_item *);
+
+const struct cmd_entry cmd_resize_window_entry = {
+	.name = "resize-window",
+	.alias = "resizew",
+
+	.args = { "aADLRt:Ux:y:", 0, 1 },
+	.usage = "[-aADLRU] [-x width] [-y height] " CMD_TARGET_PANE_USAGE " "
+		 "[adjustment]",
+
+	.target = { 't', CMD_FIND_WINDOW, 0 },
+
+	.flags = CMD_AFTERHOOK,
+	.exec = cmd_resize_window_exec
+};
+
+static enum cmd_retval
+cmd_resize_window_exec(struct cmd *self, struct cmdq_item *item)
+{
+	struct args		*args = self->args;
+	struct winlink		*wl = item->target.wl;
+	struct window		*w = wl->window;
+	struct session		*s = item->target.s;
+	const char	       	*errstr;
+	char			*cause;
+	u_int			 adjust, sx, sy;
+
+	if (args->argc == 0)
+		adjust = 1;
+	else {
+		adjust = strtonum(args->argv[0], 1, INT_MAX, &errstr);
+		if (errstr != NULL) {
+			cmdq_error(item, "adjustment %s", errstr);
+			return (CMD_RETURN_ERROR);
+		}
+	}
+
+	sx = w->sx;
+	sy = w->sy;
+
+	if (args_has(args, 'x')) {
+		sx = args_strtonum(args, 'x', WINDOW_MINIMUM, WINDOW_MAXIMUM,
+		    &cause);
+		if (cause != NULL) {
+			cmdq_error(item, "width %s", cause);
+			free(cause);
+			return (CMD_RETURN_ERROR);
+		}
+	}
+	if (args_has(args, 'y')) {
+		sy = args_strtonum(args, 'y', WINDOW_MINIMUM, WINDOW_MAXIMUM,
+		    &cause);
+		if (cause != NULL) {
+			cmdq_error(item, "height %s", cause);
+			free(cause);
+			return (CMD_RETURN_ERROR);
+		}
+	}
+
+	if (args_has(args, 'L')) {
+		if (sx >= adjust)
+			sx -= adjust;
+	} else if (args_has(args, 'R'))
+		sx += adjust;
+	else if (args_has(args, 'U')) {
+		if (sy >= adjust)
+			sy -= adjust;
+	} else if (args_has(args, 'D'))
+		sy += adjust;
+
+	if (args_has(args, 'A'))
+		default_window_size(s, w, &sx, &sy, WINDOW_SIZE_LARGEST);
+	else if (args_has(args, 'a'))
+		default_window_size(s, w, &sx, &sy, WINDOW_SIZE_SMALLEST);
+
+	options_set_number(w->options, "window-size", WINDOW_SIZE_MANUAL);
+	resize_window(w, sx, sy);
+
+	return (CMD_RETURN_NORMAL);
+}
diff --git a/cmd-select-pane.c b/cmd-select-pane.c
index a2345fe1..5cec82f2 100644
--- a/cmd-select-pane.c
+++ b/cmd-select-pane.c
@@ -54,6 +54,31 @@ const struct cmd_entry cmd_last_pane_entry = {
 	.exec = cmd_select_pane_exec
 };
 
+static void
+cmd_select_pane_redraw(struct window *w)
+{
+	struct client	*c;
+
+	/*
+	 * Redraw entire window if it is bigger than the client (the
+	 * offset may change), otherwise just draw borders.
+	 */
+
+	TAILQ_FOREACH(c, &clients, entry) {
+		if (c->session == NULL)
+			continue;
+		if (c->session->curw->window == w && tty_window_bigger(&c->tty))
+			server_redraw_client(c);
+		else {
+			if (c->session->curw->window == w)
+				c->flags |= CLIENT_REDRAWBORDERS;
+			if (session_has(c->session, w))
+				c->flags |= CLIENT_REDRAWSTATUS;
+		}
+
+	}
+}
+
 static enum cmd_retval
 cmd_select_pane_exec(struct cmd *self, struct cmdq_item *item)
 {
@@ -87,15 +112,14 @@ cmd_select_pane_exec(struct cmd *self, struct cmdq_item *item)
 			window_redraw_active_switch(w, lastwp);
 			if (window_set_active_pane(w, lastwp)) {
 				cmd_find_from_winlink(current, wl, 0);
-				server_status_window(w);
-				server_redraw_window_borders(w);
+				cmd_select_pane_redraw(w);
 			}
 		}
 		return (CMD_RETURN_NORMAL);
 	}
 
 	if (args_has(args, 'm') || args_has(args, 'M')) {
-		if (args_has(args, 'm') && !window_pane_visible(wp))
+		if (args_has(args, 'm'))
 			return (CMD_RETURN_NORMAL);
 		lastwp = marked_pane.wp;
 
@@ -168,16 +192,11 @@ cmd_select_pane_exec(struct cmd *self, struct cmdq_item *item)
 	if (wp == w->active)
 		return (CMD_RETURN_NORMAL);
 	server_unzoom_window(wp->window);
-	if (!window_pane_visible(wp)) {
-		cmdq_error(item, "pane not visible");
-		return (CMD_RETURN_ERROR);
-	}
 	window_redraw_active_switch(w, wp);
 	if (window_set_active_pane(w, wp)) {
 		cmd_find_from_winlink_pane(current, wl, wp, 0);
 		hooks_insert(s->hooks, item, current, "after-select-pane");
-		server_status_window(w);
-		server_redraw_window_borders(w);
+		cmd_select_pane_redraw(w);
 	}
 
 	return (CMD_RETURN_NORMAL);
diff --git a/cmd-set-option.c b/cmd-set-option.c
index bdc42cae..c4b82004 100644
--- a/cmd-set-option.c
+++ b/cmd-set-option.c
@@ -18,6 +18,7 @@
 
 #include <sys/types.h>
 
+#include <fnmatch.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -260,7 +261,7 @@ cmd_set_option_exec(struct cmd *self, struct cmdq_item *item)
 	}
 	if (strcmp(name, "pane-border-status") == 0) {
 		RB_FOREACH(w, windows, &windows)
-			layout_fix_panes(w, w->sx, w->sy);
+			layout_fix_panes(w);
 	}
 	RB_FOREACH(s, sessions, &sessions)
 		status_update_saved(s);
@@ -297,7 +298,8 @@ cmd_set_option_set(struct cmd *self, struct cmdq_item *item, struct options *oo,
 	int					 append = args_has(args, 'a');
 	struct options_entry			*o;
 	long long				 number;
-	const char				*errstr;
+	const char				*errstr, *new;
+	char					*old;
 	key_code				 key;
 
 	oe = options_table_entry(parent);
@@ -310,7 +312,16 @@ cmd_set_option_set(struct cmd *self, struct cmdq_item *item, struct options *oo,
 
 	switch (oe->type) {
 	case OPTIONS_TABLE_STRING:
+		old = xstrdup(options_get_string(oo, oe->name));
 		options_set_string(oo, oe->name, append, "%s", value);
+		new = options_get_string(oo, oe->name);
+		if (oe->pattern != NULL && fnmatch(oe->pattern, new, 0) != 0) {
+			options_set_string(oo, oe->name, 0, "%s", old);
+			free(old);
+			cmdq_error(item, "value is invalid: %s", value);
+			return (-1);
+		}
+		free(old);
 		return (0);
 	case OPTIONS_TABLE_NUMBER:
 		number = strtonum(value, oe->minimum, oe->maximum, &errstr);
diff --git a/cmd-split-window.c b/cmd-split-window.c
index 378576ff..f5dde751 100644
--- a/cmd-split-window.c
+++ b/cmd-split-window.c
@@ -147,7 +147,7 @@ cmd_split_window_exec(struct cmd *self, struct cmdq_item *item)
 	}
 	environ_free(env);
 
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 	server_redraw_window(w);
 
 	if (!args_has(args, 'd')) {
diff --git a/cmd-swap-pane.c b/cmd-swap-pane.c
index 7283bf53..1de272c4 100644
--- a/cmd-swap-pane.c
+++ b/cmd-swap-pane.c
@@ -105,8 +105,6 @@ cmd_swap_pane_exec(struct cmd *self, struct cmdq_item *item)
 			window_set_active_pane(dst_w, src_wp);
 		} else {
 			tmp_wp = dst_wp;
-			if (!window_pane_visible(tmp_wp))
-				tmp_wp = src_wp;
 			window_set_active_pane(src_w, tmp_wp);
 		}
 	} else {
diff --git a/cmd-switch-client.c b/cmd-switch-client.c
index 180635df..6181073d 100644
--- a/cmd-switch-client.c
+++ b/cmd-switch-client.c
@@ -128,6 +128,7 @@ cmd_switch_client_exec(struct cmd *self, struct cmdq_item *item)
 	c->session = s;
 	if (~item->shared->flags & CMDQ_SHARED_REPEAT)
 		server_client_set_key_table(c, NULL);
+	tty_update_client_offset(c);
 	status_timer_start(c);
 	notify_client("client-session-changed", c);
 	session_update_activity(s, NULL);
diff --git a/cmd.c b/cmd.c
index e432ae4a..5df30798 100644
--- a/cmd.c
+++ b/cmd.c
@@ -80,6 +80,7 @@ extern const struct cmd_entry cmd_refresh_client_entry;
 extern const struct cmd_entry cmd_rename_session_entry;
 extern const struct cmd_entry cmd_rename_window_entry;
 extern const struct cmd_entry cmd_resize_pane_entry;
+extern const struct cmd_entry cmd_resize_window_entry;
 extern const struct cmd_entry cmd_respawn_pane_entry;
 extern const struct cmd_entry cmd_respawn_window_entry;
 extern const struct cmd_entry cmd_rotate_window_entry;
@@ -166,6 +167,7 @@ const struct cmd_entry *cmd_table[] = {
 	&cmd_rename_session_entry,
 	&cmd_rename_window_entry,
 	&cmd_resize_pane_entry,
+	&cmd_resize_window_entry,
 	&cmd_respawn_pane_entry,
 	&cmd_respawn_window_entry,
 	&cmd_rotate_window_entry,
diff --git a/format.c b/format.c
index d3da9eb7..cea338a1 100644
--- a/format.c
+++ b/format.c
@@ -1330,8 +1330,6 @@ format_defaults_session(struct format_tree *ft, struct session *s)
 
 	format_add(ft, "session_name", "%s", s->name);
 	format_add(ft, "session_windows", "%u", winlink_count(&s->windows));
-	format_add(ft, "session_width", "%u", s->sx);
-	format_add(ft, "session_height", "%u", s->sy);
 	format_add(ft, "session_id", "$%u", s->id);
 
 	sg = session_group_contains(s);
@@ -1492,18 +1490,14 @@ format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
 		format_add(ft, "pane_dead_status", "%d", WEXITSTATUS(status));
 	format_add(ft, "pane_dead", "%d", wp->fd == -1);
 
-	if (window_pane_visible(wp)) {
-		format_add(ft, "pane_left", "%u", wp->xoff);
-		format_add(ft, "pane_top", "%u", wp->yoff);
-		format_add(ft, "pane_right", "%u", wp->xoff + wp->sx - 1);
-		format_add(ft, "pane_bottom", "%u", wp->yoff + wp->sy - 1);
-		format_add(ft, "pane_at_left", "%d", wp->xoff == 0);
-		format_add(ft, "pane_at_top", "%d", wp->yoff == 0);
-		format_add(ft, "pane_at_right", "%d",
-		    wp->xoff + wp->sx == w->sx);
-		format_add(ft, "pane_at_bottom", "%d",
-		    wp->yoff + wp->sy == w->sy);
-	}
+	format_add(ft, "pane_left", "%u", wp->xoff);
+	format_add(ft, "pane_top", "%u", wp->yoff);
+	format_add(ft, "pane_right", "%u", wp->xoff + wp->sx - 1);
+	format_add(ft, "pane_bottom", "%u", wp->yoff + wp->sy - 1);
+	format_add(ft, "pane_at_left", "%d", wp->xoff == 0);
+	format_add(ft, "pane_at_top", "%d", wp->yoff == 0);
+	format_add(ft, "pane_at_right", "%d", wp->xoff + wp->sx == w->sx);
+	format_add(ft, "pane_at_bottom", "%d", wp->yoff + wp->sy == w->sy);
 
 	format_add(ft, "pane_in_mode", "%d", wp->screen != &wp->base);
 	if (wp->mode != NULL)
diff --git a/input-keys.c b/input-keys.c
index 85dc2591..d3ff0dc0 100644
--- a/input-keys.c
+++ b/input-keys.c
@@ -247,8 +247,6 @@ input_key_mouse(struct window_pane *wp, struct mouse_event *m)
 
 	if ((mode & ALL_MOUSE_MODES) == 0)
 		return;
-	if (!window_pane_visible(wp))
-		return;
 	if (cmd_mouse_at(wp, m, &x, &y, 0) != 0)
 		return;
 
diff --git a/layout-custom.c b/layout-custom.c
index 1b8f576e..9886afe1 100644
--- a/layout-custom.c
+++ b/layout-custom.c
@@ -167,7 +167,7 @@ layout_parse(struct window *w, const char *layout)
 
 	/* Update pane offsets and sizes. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, lc->sx, lc->sy);
+	layout_fix_panes(w);
 
 	/* Then resize the layout back to the original window size. */
 	layout_resize(w, sx, sy);
diff --git a/layout-set.c b/layout-set.c
index 5055f672..b9769ed5 100644
--- a/layout-set.c
+++ b/layout-set.c
@@ -148,7 +148,7 @@ layout_set_even(struct window *w, enum layout_type type)
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 
 	layout_print_cell(w->layout_root, __func__, 1);
 
@@ -284,7 +284,7 @@ layout_set_main_h(struct window *w)
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 
 	layout_print_cell(w->layout_root, __func__, 1);
 
@@ -408,7 +408,7 @@ layout_set_main_v(struct window *w)
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 
 	layout_print_cell(w->layout_root, __func__, 1);
 
@@ -511,7 +511,7 @@ layout_set_tiled(struct window *w)
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 
 	layout_print_cell(w->layout_root, __func__, 1);
 
diff --git a/layout.c b/layout.c
index e1112ffa..c71dc7e5 100644
--- a/layout.c
+++ b/layout.c
@@ -253,71 +253,29 @@ layout_need_status(struct layout_cell *lc, int at_top)
 
 /* Update pane offsets and sizes based on their cells. */
 void
-layout_fix_panes(struct window *w, u_int wsx, u_int wsy)
+layout_fix_panes(struct window *w)
 {
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
-	u_int			 sx, sy;
-	int			 shift, status, at_top;
+	int			 shift, status;
 
 	status = options_get_number(w->options, "pane-border-status");
-	at_top = (status == 1);
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if ((lc = wp->layout_cell) == NULL)
 			continue;
 
 		if (status != 0)
-			shift = layout_need_status(lc, at_top);
+			shift = layout_need_status(lc, status == 1);
 		else
 			shift = 0;
 
 		wp->xoff = lc->xoff;
 		wp->yoff = lc->yoff;
 
-		if (shift && at_top)
+		if (shift && status == 1)
 			wp->yoff += 1;
 
-		/*
-		 * Layout cells are limited by the smallest size of other cells
-		 * within the same row or column; if this isn't the case
-		 * resizing becomes difficult.
-		 *
-		 * However, panes do not have to take up their entire cell, so
-		 * they can be cropped to the window edge if the layout
-		 * overflows and they are partly visible.
-		 *
-		 * This stops cells being hidden unnecessarily.
-		 */
-
-		/*
-		 * Work out the horizontal size. If the pane is actually
-		 * outside the window or the entire pane is already visible,
-		 * don't crop.
-		 */
-		if (lc->xoff >= wsx || lc->xoff + lc->sx < wsx)
-			sx = lc->sx;
-		else {
-			sx = wsx - lc->xoff;
-			if (sx < 1)
-				sx = lc->sx;
-		}
-
-		/*
-		 * Similarly for the vertical size; the minimum vertical size
-		 * is two because scroll regions cannot be one line.
-		 */
-		if (lc->yoff >= wsy || lc->yoff + lc->sy < wsy)
-			sy = lc->sy;
-		else {
-			sy = wsy - lc->yoff;
-			if (sy < 2)
-				sy = lc->sy;
-		}
-
-		if (shift)
-			sy -= 1;
-
-		window_pane_resize(wp, sx, sy);
+		window_pane_resize(wp, lc->sx, lc->sy - shift);
 	}
 }
 
@@ -491,8 +449,7 @@ layout_init(struct window *w, struct window_pane *wp)
 	lc = w->layout_root = layout_create_cell(NULL);
 	layout_set_size(lc, w->sx, w->sy, 0, 0);
 	layout_make_leaf(lc, wp);
-
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 }
 
 void
@@ -550,7 +507,7 @@ layout_resize(struct window *w, u_int sx, u_int sy)
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(lc);
-	layout_fix_panes(w, sx, sy);
+	layout_fix_panes(w);
 }
 
 /* Resize a pane to an absolute size. */
@@ -610,7 +567,7 @@ layout_resize_layout(struct window *w, struct layout_cell *lc,
 
 	/* Fix cell offsets. */
 	layout_fix_offsets(w->layout_root);
-	layout_fix_panes(w, w->sx, w->sy);
+	layout_fix_panes(w);
 	notify_window("window-layout-changed", w);
 }
 
@@ -717,7 +674,7 @@ void
 layout_assign_pane(struct layout_cell *lc, struct window_pane *wp)
 {
 	layout_make_leaf(lc, wp);
-	layout_fix_panes(wp->window, wp->window->sx, wp->window->sy);
+	layout_fix_panes(wp->window);
 }
 
 /* Calculate the new pane size for resized parent. */
@@ -1037,7 +994,7 @@ layout_close_pane(struct window_pane *wp)
 	/* Fix pane offsets and sizes. */
 	if (w->layout_root != NULL) {
 		layout_fix_offsets(w->layout_root);
-		layout_fix_panes(w, w->sx, w->sy);
+		layout_fix_panes(w);
 	}
 	notify_window("window-layout-changed", w);
 }
@@ -1094,7 +1051,7 @@ layout_spread_out(struct window_pane *wp)
 	do {
 		if (layout_spread_cell(w, parent)) {
 			layout_fix_offsets(parent);
-			layout_fix_panes(w, w->sx, w->sy);
+			layout_fix_panes(w);
 			break;
 		}
 	} while ((parent = parent->parent) != NULL);
diff --git a/options-table.c b/options-table.c
index 2b6b794b..0776f0b7 100644
--- a/options-table.c
+++ b/options-table.c
@@ -59,6 +59,9 @@ static const char *options_table_pane_status_list[] = {
 static const char *options_table_set_clipboard_list[] = {
 	"off", "external", "on", NULL
 };
+static const char *options_table_window_size_list[] = {
+	"largest", "smallest", "manual", NULL
+};
 
 /* Top-level options. */
 const struct options_table_entry options_table[] = {
@@ -193,6 +196,13 @@ const struct options_table_entry options_table[] = {
 	  .default_str = _PATH_BSHELL
 	},
 
+	{ .name = "default-size",
+	  .type = OPTIONS_TABLE_STRING,
+	  .scope = OPTIONS_TABLE_SESSION,
+	  .pattern = "[0-9]*x[0-9]*",
+	  .default_str = "80x24"
+	},
+
 	{ .name = "destroy-unattached",
 	  .type = OPTIONS_TABLE_FLAG,
 	  .scope = OPTIONS_TABLE_SESSION,
@@ -588,22 +598,6 @@ const struct options_table_entry options_table[] = {
 	  .default_num = 1
 	},
 
-	{ .name = "force-height",
-	  .type = OPTIONS_TABLE_NUMBER,
-	  .scope = OPTIONS_TABLE_WINDOW,
-	  .minimum = 0,
-	  .maximum = INT_MAX,
-	  .default_num = 0
-	},
-
-	{ .name = "force-width",
-	  .type = OPTIONS_TABLE_NUMBER,
-	  .scope = OPTIONS_TABLE_WINDOW,
-	  .minimum = 0,
-	  .maximum = INT_MAX,
-	  .default_num = 0
-	},
-
 	{ .name = "main-pane-height",
 	  .type = OPTIONS_TABLE_NUMBER,
 	  .scope = OPTIONS_TABLE_WINDOW,
@@ -770,6 +764,13 @@ const struct options_table_entry options_table[] = {
 	  .default_str = "default"
 	},
 
+	{ .name = "window-size",
+	  .type = OPTIONS_TABLE_CHOICE,
+	  .scope = OPTIONS_TABLE_WINDOW,
+	  .choices = options_table_window_size_list,
+	  .default_num = WINDOW_SIZE_LARGEST
+	},
+
 	{ .name = "window-style",
 	  .type = OPTIONS_TABLE_STYLE,
 	  .scope = OPTIONS_TABLE_WINDOW,
diff --git a/resize.c b/resize.c
index 1c9694da..faaa044d 100644
--- a/resize.c
+++ b/resize.c
@@ -22,144 +22,224 @@
 
 #include "tmux.h"
 
-/*
- * Recalculate window and session sizes.
- *
- * Every session has the size of the smallest client it is attached to and
- * every window the size of the smallest session it is attached to.
- *
- * So, when a client is resized or a session attached to or detached from a
- * client, the window sizes must be recalculated. For each session, find the
- * small