bug#23966: 25.1.50; Frame resizing due to tool bar + Gnus

[martin rudalics <rudalics@gmx.at>]

 >> ‘frame-height’ is not necessarily a reliable reflection of what you see
 >> on screen.
 >
 > Why not?

Because of rounding.  Tool bar, menu bar and scroll bars do not have
necessarily sizes that are multiples of a frame's default character
size.  And often you're losing pixels when the frame gets maximized or
‘frame-resize-pixelwise’ is non-nil during resizing.

 > What's more reliable?

Everything that counts in pixels like ‘frame-pixel-height’.

 >> ... in an emacs -Q of the release version I get
 >
 > I assume you mean from emacs-25?

Yes.

 > With 24.5 I get "Symbol's function
 > definition is void: frame-geometry".

Indeed.

 >> What do you get with my modifications?
 >
 > On emacs-25 with -Q and frame-resize-pixelwise nil:
[...]
 > Other buffer; frame pixel height: 608  toolbar height: 53
[...]
 >
 > On master with -Q and frame-resize-pixelwise nil the results were the
 > same except for the third to last line:
 >
 > Other buffer; frame pixel height: 608  toolbar height: 45

Not here.  I get 648 and 44 in both cases.

 > On emacs-25 with -Q frame-resize-pixelwise t:
 >
 > Emacs started; frame pixel height: 576  toolbar height: 53
[...]
 > Final; frame pixel height: 666  toolbar height: 53

So your frame has grown by 90 pixels.  Remarkable.  BTW setting
‘frame-inhibit-implied-resize’ to t would avoid that.

 > On master with -Q and frame-resize-pixelwise t the results were the
 > same except for the last three lines:
 >
 > Other buffer; frame pixel height: 621  toolbar height: 45
 > Back to Summary buffer; frame pixel height: 658  toolbar height: 8
 > Final; frame pixel height: 658  toolbar height: 53

Here all lines are the same, again.

The problem is not GTK specific.  Lucid and Motif behave similarly.  I
suppose that just enabling ‘tool-bar-mode’ is not sufficient to make a
gnus tool bar once gnus has started.  Maybe this deficiency is inherent
to ‘tool-bar-mode’ itself.  But it would be interesting to find out
who's responsible for making such small (8 pixels in your, 35 pixels in
my case) tool bars in the first place.

martin