bug#7307: 24.0.50; Mode line had more than just dashes removed

[Stephen Berman]

This change:

2010-10-18  Julien Danjou  <julien@danjou.info>

        * bindings.el: Remove end dashes in default mode-line-format.

not only removed the dashes at the end of the mode line, but also the
help string in a tool tip together with the altered mouse pointer, which
serves as a visual cue that the mode line is draggable (with vertically
split windows).  I think these help indicators should be restored.
Unfortunately, there is no mode line construct that inserts spaces to
the end of the window like "%-" inserts dashed.  So I tried make-string
and it seems to DTRT.  The only problem is specifying the length of the
string: (window-width) as the maximum possible length fails here,
because the mode line is constructed before the window-system frame, and
has a value of just 10.  So I just picked 200 as a plausible maximum.
Maybe there's a better way, but this seems to work ok.

*** /home/steve/bzr/emacs/trunk/lisp/bindings.el        2010-10-24 
13:56:16.000000000 +0200
--- /home/steve/bzr/emacs/quickfixes/lisp/bindings.el   2010-10-30 
00:39:06.000000000 +0200
***************
*** 336,342 ****
         'mode-line-modes
         `(which-func-mode ("" which-func-format ,spaces))
         `(global-mode-string ("" global-mode-string ,spaces))
!        `(:eval (unless (display-graphic-p)
                   ,(propertize "-%-" 'help-echo help-echo)))))
         (standard-mode-line-modes
        (list
--- 336,343 ----
         'mode-line-modes
         `(which-func-mode ("" which-func-format ,spaces))
         `(global-mode-string ("" global-mode-string ,spaces))
!        `(:eval (if (display-graphic-p)
!                    ,(propertize (make-string 200 32) 'help-echo help-echo)
                   ,(propertize "-%-" 'help-echo help-echo)))))
         (standard-mode-line-modes
        (list