On Mon, Sep 14, 2015 at 3:39 PM, martin rudalics <rudalics@gmx.at> wrote:

> >>> No, ns-auto-hide-menu-bar does not move the frame at all.
> >>
> >> OK.  But doesn't it remove the constraint that a frame's rectangle must
> >> start somehwere at or below (0, 0)?
> >
> > When the menu bar is visible, OS X doesn't allow windows above the menu
> > bar.
>
> I'm not sure I understand: Do you mean here "OS X doesn't allow windows
> above the top of the screen"?


It's not possible to place a window above the top of the screen if the menu
bar is visible. (If I remember correctly, I haven't worked in this for
quite some time.)


> However, OS X allows an application to place a window above the
> > top of the screen -- the code in Emacs simply ensures that Emacs itself
> > doesn't hinder this.
>
> Does this "OS X allows an application to place a window above the top of
> the screen" hold _only_ when the menu bar is hidden or does it hold
> regardless of that?  What's such a restriction good for anyway?


Only when it is hidden (again, if I remember correctly). The reason, I
guess, is to ensure that no application would ever land underneath the menu
bar.



> > -- the code in Emacs simply ensures that Emacs itself
> > doesn't hinder this.
>
> Because Emacs "normally" advices OS X to constrain the frame to the
> screen.  Correct?


No, not really. A frame can stretch below the screen, and (I have to
double-check this one when I get home) to either side.

When the menu bar is hidden, you can also do this above the screen.



> > By the way, when I use Win32, I also place the title bar above the top of
> > the screen,
>
> Why?  Do you never use the fullscreen feature?


No, never.

The reason is that I want the Emacs frame to use maximal height, but at the
same time I like to control the width so that I can have six side-by-side
windows each with exactly 79 columns. (I use two 1600x1200 monitors and a
6x8 font, with the help of Follow mode I can see 888 consecutive lines of
code.)


> so this is not a feature that is unique to the OS X port. Of
> > course, for a frame the be placed above the top of the screen, the user
> > must explicitly placed it there. A frame should never "just happen" to be
> > placed above the top of the screen.
>
> It will happen when it's too large and you specify negative values for
> its position.


Yes, but I would see that as though the user explicitly has asked for that
case.

The important thing is that it doesn't happen when a user creates a new
frame using `C-x 5 2' or call `make-frame' with default parameters etc.

/ Anders