Support -x and -y for new-session to specify the initial size of the

window if created detached with -d.

tmux.1

@@ -591,6 +591,8 @@ Lock all clients attached to
 .Op Fl n Ar window-name
 .Op Fl s Ar session-name
 .Op Fl t Ar target-session
+.Op Fl x Ar width
+.Op Fl y Ar height
 .Op Ar shell-command
 .Xc
 .D1 (alias: Ic new )
@@ -604,6 +606,13 @@ is given.
 and
 .Ar shell-command
 are the name of and shell command to execute in the initial window.
+If
+.Fl d
+is used,
+.Fl x
+and
+.Fl y
+specify the size of the initial window (80 by 24 if not given).
 .Pp
 If run from a terminal, any
 .Xr termios 4