See bug 163317 for an example of the confusion this problem can cause.

The most simple way to create an HIG compliant dialog should be use this code in
GtkDialog init function:

	dialog->vbox = gtk_vbox_new (FALSE, 24);

	gtk_container_set_border_width (GTK_CONTAINER (dialog->vbox), 12);
	gtk_container_add (GTK_CONTAINER (dialog), dialog->vbox);

	gtk_widget_show (dialog->vbox);

	dialog->action_area = gtk_hbutton_box_new ();

	gtk_box_set_spacing (GTK_BOX (dialog->action_area), 6);
	gtk_box_pack_end (GTK_BOX (dialog->vbox), dialog->action_area,
	                  FALSE, TRUE, 0);
	gtk_button_box_set_layout (GTK_BUTTON_BOX (dialog->action_area),
                                   GTK_BUTTONBOX_END);

	gtk_widget_show (dialog->action_area);


Advantages:
- the dialog spacing/border sizes will be HIG compliant

- developers/UI designers can ignore spacing/padding of the dialog and take care
only of the stuff they put inside the dialog. So when you add a container in the
dialog it's well aligned (e.g. a GtkNotebook).

- all dialogs will have the same spacing/border size


Notes:

- this will break API compatibility with 2.x series (no more separator
properties/functions and no more content_area_border, button_spacing, and
action_area_border styles)

- dialog->vbox spacing and border width could be editable as style properties.
This could be useful for LargePrint a11y themes. But ask a11y people before do it.

- the gtk_box_set_spacing (GTK_BOX (dialog->action_area), 6); call inside
GtkDialog init function is bad idea too. The default spacing of a GtkButtonBox
should be 6 pixel, maybe editable as style, so you don't have to change.

- Do we have to put the separator for Windows(TM)?

Enhancements:

- Could we use a different minimum padding for Help button?

	[  Help  ]  <-24px->  [  Apply ] [ Cancel ] [   OK   ]
                                        ^          ^
                                        ^----------^---6 px

- Could we add a default shortcut (F1) to activate Help button response?

About buttons spacing take a look at:

http://developer.apple.com/documentation/UserExperience/Conceptual/OSXHIGuidelines/XHIGDialogs/chapter_9_section_3.html

Created attachment 51135 [details] [review]
Proposed patch

This patch makes the GtkDialog and GtkMessageDialog GNOME HIG compliant by
default.  Applications will no longer need to adjust the border width of the
dialog, dialog->vbox, and dialog->action_area themselves.  

Also, it removes the dialog title from the GtkMessageDialogs per the HIG.  And,
it fixes the spacing between buttons in the dialog->action_area to be HIG
compliant.

If the above patch (or something similar) is committed to CVS, then the
following code should be removed from GNOME applications.

  gtk_container_set_border_width (GTK_CONTAINER (dialog), 5);
  gtk_container_set_border_width (GTK_CONTAINER (GTK_DIALOG (dialog)->vbox), 5);
  gtk_box_set_spacing (GTK_BOX (GTK_DIALOG (dialog)->vbox), 2);
  gtk_window_set_title (GTK_WINDOW (dialog), "");

I can help remove this code from GNOME, since I am responsible for most of it
anyhow.

*** Bug 165083 has been marked as a duplicate of this bug. ***

The title issue is covered by bug 310443, which also has a patch

Created attachment 51308 [details] [review]
Proposed patch

Same as my previous patch except I removed the title issue fix since it is
covered by a patch in bug 310443.

Created attachment 51310 [details] [review]
Proposed patch (Font Selection Dialog)

This patch makes the Font Selection dialog HIG compliant.  It assumes the
previous patch for GtkDialog and GtkMessageDialog was applied.

Created attachment 51311 [details]
Screenshot of the Font Selection dialog.

Created attachment 51317 [details] [review]
Proposed patch (Input Dialog)

Created attachment 51318 [details]
Screenshot of the Input dialog (Axes tab).

Created attachment 51319 [details]
Screenshot of the Input dialog (Keys tab).

Created attachment 51346 [details] [review]
Proposed patch (Color Selection Dialog)

Created attachment 51347 [details]
Screenshot of the Color Selection dialog.

Created attachment 51348 [details] [review]
Updated proposed patch (Font Selection Dialog)

The previously proposed patch for the Font Selection dialog was missing one
line.

*** Bug 328018 has been marked as a duplicate of this bug. ***

Created attachment 58589 [details] [review]
all-in-one patch

This patch contains all above patches (to gtkmessagedialog.c, gtkcolorsel.c gtkcolorseldialog.c gtkinputdialog.c gtkfontsel.c) in one, with the exception of the changes to gtkdialog.c.
I think changing the default spacings of gtkdialog will break too much existing dialogues that rely on the default values, and make them of broken appearance. This patch instead sets the spacings/borders for each dialogue. IMHO this patch is therefore appropriate for a 2.x release.

The patch has string changes (why ?), so it will certainly not go into 2.8.x

Sorry, I meant that it's appropriate to add to an unstable gtk 2.odd.x release, as opposed to the 'gtk 3' that comment 0 speaks of :)

The string changes seem to be mostly accelerator _ added/removed, not sure why it was done (I can't see the input dialogue since I have no inputs)...

Thanks for combining these patches into one.  

The string changes were also part of the HIG fixes. 
  * remove trailing space from label as per HIG
  * add or remove mnemonics as per HIG
  * add missing colon to labels as per HIG
  * fix capitalization as per HIG

Any chance of this stuff getting fixed for GTK+ 2.10 / Project Ridley?

I think I'm fine with most of the changes, but I don't think we should 
just ignore the message-border style property. If I understood the
code correctly, we should probably do something like

  if (parent)
    {
      gtk_widget_style_get (widget, "message-border",
                            &border_width, NULL);
      
      gtk_container_set_border_width (GTK_CONTAINER (parent),
                                      MAX (0, border_width - 7));
    }

to account for the fact that the hbox only receives 5 of the default 12
in the default setup.

Created attachment 61020 [details] [review]
Updated all-in-one proposed patch

Matthais, Thanks for your feedback.  I updated the all-in-one patch with the changes you recommended in comment #23.

2006-03-10  Matthias Clasen  <mclasen@redhat.com>

	Apply a patch from Dennis Cranston to make dialogs more
	consistent  (#163850)
	
	* gtk/gtkcolorsel.c (make_label_spinbutton): Left-align labels.
	
	* gtk/gtkfontsel.c (gtk_font_selection_init): 
	* gtk/gtkfontsel.c (gtk_font_selection_dialog_init): 
	* gtk/gtkcolorsel.c (gtk_color_selection_init): 
	* gtk/gtkcolorseldialog.c (gtk_color_selection_dialog_init): 
	* gtk/gtkinputdialog.c (gtk_input_dialog_init): Update the layout
	of the dialog to follow HIG recommendations. Also update labels.

	* gtk/gtkmessagedialog.c (gtk_message_dialog_init): HIG-compatible 
	spacing.
	(gtk_message_dialog_font_size_change): Merged into 
	 gtk_message_dialog_style_set.

Created attachment 61058 [details] [review]
additional patch to change default button spacing

The other GtkDialog spacings can't be changed compatibly, but IMHO changing the default button spacing to HIG-default of 6px should be compatible enough; what do you think?

Created attachment 61059 [details] [review]
Patch to fix a mnemonic conflict.

The patch applied to CVS uses the 'O' for the "Opacity" label mnemonic which will conflict with the 'O' mnemonic for the "OK" button.  This patch fixes the mnemonic conflict.

Created attachment 61069 [details] [review]
Patch to fix a mnemonic conflict and missing colon.

Two label fixes from the all-in-one patch were not applied to CVS.  

2006-03-10  Dennis Cranston  <dennis_cranston@yahoo.com>

	* gtk/gtkcolorsel.c: (gtk_color_selection_init): Fix a mnemonic
	conflict.  Add a missing colon to the pallete label.

Comment on attachment 61058 [details] [review]
additional patch to change default button spacing

Can this patch be committed too? It's just changing the default dialog buttonbox spacing from 10 to 6 (HIG) and should be sufficiently compatible...