Re: Temporarily select-window, without updating mode-line face and cursor fill?

[martin rudalics <rudalics@gmx.at>]

 > For calculating the line number in a window which may or may not be
 > selected, (format-mode-line "%l” 0 win) has a window argument, but it
 > does *not* have a position argument.  It takes its position from (as
 > far as I can tell) the window-point of its window argument.  So I need
 > to move window-point and immediately restore it if I want to use
 > format-mode-line.  If the window were selected, a simple
 > save-excursion would be enough.  But I cannot first select the window
 > or I get “mode line flashing".  I need a mythical
 > `save-excursion-in-window', if you will.

If you just want to evaluate forms like the above (format-mode-line "%l"
0 win) then all I said does not apply.  I thought you wanted to do such
things via an :eval in the mode line format.

So I probably misunderstood you.  If all you want to do is to exploit
the "%l" construct for getting the line number at window start or window
end, then `set-window-point' should at least not harm (though it might
not work due to scrolling).

 > But I will certainly need set-window-start for handling mouse-based
 > events on the mode line (click/drag/scroll).  Perhaps I didn’t make it
 > clear that set-window-start will only be called in mouse-based event
 > callbacks on the mode line; apologies if so.  If even this is
 > problematic in your view, could you clarify the sort of “trouble” it
 > would cause?  Other mouse events in the mode-line call things like
 > ‘previous-buffer, so it’s not clear to me why set-window-start would
 > lead to any special issues when driven by mouse events.

If you mean `set-window-start' as the effect (or a side effect) of a
mouse-based event on the mode line I see no problem.

martin