bug#25511: 26.0.50; modify-frame-parameters modifies undesignated parameter?

[Katsumi Yamaoka <yamaoka@jpl.org>]

On Mon, 23 Jan 2017 09:03:35 +0100, martin rudalics wrote:
>> The coordinates start with (0 0) and (256 1080) respectively[1].
>> In that situation, the following script makes a new frame protrude
>> to the left from the down screen:
>>
>> (let ((frame (make-frame)))
>>    (modify-frame-parameters frame '((top . 1200))))

> Why don't you use

> (make-frame '((top . 1200)))

> in the first place?  This should tell the window manager right away what
> position you want before making the frame visible.  If this does not
> work as intended, we shall have to investigate it.

Yes, it and even (make-frame) work with no problem.

> As a general rule: Never set a frame parameter right after creating a
> new frame.

Ok, I can modify some codes similar to it.

>> On the new frame, (frame-parameter nil 'left) returns 8, that is
>> outside of the down screen.  This happens whichever the original
>> frame (that runs the script) exists in the up screen or the down
>> screen.  As mentioned above, a new frame did not protrude from
>> the down screen last week.  Here is a workaround:
>>
>> (let ((frame (make-frame)))
>>    (sit-for 0)
>>    (modify-frame-parameters frame '((top . 1200))))
>>
>> But it is needless, isn't it?

> IIUC your approach worked because of a busy loop in x_make_frame_visible
> which has been removed a few days ago.  I back its removal so you should
> be able to do without it.

I found the change in question in git log after sending the
report.  I don't ask you to revert it as it seems to have been
a burden sort of.

>> [1] The values of left and top frame parameters seem to indicate
>>      that of a window of an Emacs frame, so we have to increase
>>      the values some extent.

> I'm not sure I can follow you here.  The `top' and `left' frame
> parameters usually indicate the top/left position of the window manager
> frame that has reparented the outermost widget of your Emacs frame.
> What do you have to "increase"?

In order not to hide the matte that includes the title bar, the
menu bar, and the tool bar.  In reality on Cygwin, the form

(make-frame '((left . 0) (top . 0)))

doesn't work as expected; the new frame appears on the down
screen and the position is erratic.  The minimum values that
display a new frame fully on the top-left corner of the upper
screen is:

(make-frame '((left . 0) (top . 1)))

But frame-parameters shows left=8 and top=32 in that case.

Anyway thanks for your help.  I will close this bug later.

Regards,