bug#11732: Follow-up to bug#11732

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 29 Jun 2018 10:43:12 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: 11732@debbugs.gnu.org
> 
> I now tried on my standard XP machine and do not see any adverse
> effects with file, directory and font dialog boxes.  Maybe it's
> related to the fact that I have "focus follows mouse" plus
> "autoraise".  Could you try with such a setting?

Will do, just not today.

>  > +	  SetWindowPos (dialog, HWND_TOPMOST, 0, 0, 0, 0,
>  > +			SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE
>  > +			| SWP_NOOWNERZORDER);
>  > +	  SetWindowPos (FRAME_W32_WINDOW (SELECTED_FRAME ()),
>  > +			dialog, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
> 
> What was the more or less precise rationale for this unless it was
> pure experimenting (in particular the SWP_NOACTIVATE in the first
> call)?

SWP_NOACTIVATE was just a copy-paste from similar calls elsewhere.
The rationale for the code was to tell windows to put the frame from
which the file-selection dialog popped behind the dialog.  If
w32_dialog_in_progress is meant to do that, I don't understand how it
does that; can you explain?

(Btw, as long as we are discussing this: the above-suspended value of
the z-group frame parameter appears to be completely undocumented.)

> The patch does not have any (adverse) effects here so if it
> solves the problem for you, I see no problem applying it.

OK.

>  > then how do
>  > we solve a similar problem in x-select-font?  It doesn't have a
>  > callback function, and if I try adding one, the appearance of the
>  > dialog changes(??) and the OK and CANCEL buttons no longer work.
> 
> Can you send me the code you tried?

Below.  It's possible I've put the code in the wrong WM_* message, but
I'm really stabbing in the dark in these matters.

> In w32_dialog_in_progress I tried to solve a relatively simple
> problem: When a frame is in the TOPMOST group and I start a dialog,
> that frame would obscure the dialog box.  So I temporarily remove the
> frame from the TOPMOST group and move it back when the dialog ends.

Can you show me some Lisp to try this situation?

Here's the patch I used with the font-selection dialog:

--- src/w32font.c~	2018-01-03 13:09:26.000000000 +0200
+++ src/w32font.c	2018-06-27 18:19:04.140101200 +0300
@@ -2505,6 +2505,24 @@ compute_metrics (HDC dc, struct w32font_
     metrics->status = W32METRIC_FAIL;
 }
 
+static UINT_PTR CALLBACK
+font_dialog_callback (HWND hdlg, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+  static HWND cf_hwnd;
+
+  if (msg == WM_INITDIALOG)
+    cf_hwnd = ((CHOOSEFONT *)lParam)->hwndOwner;
+
+  if (msg == WM_NOTIFY)
+    {
+      SetWindowPos (hdlg, HWND_NOTOPMOST, 0, 0, 0, 0,
+		    SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE
+		    | SWP_NOOWNERZORDER);
+      SetWindowPos (cf_hwnd, hdlg, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
+    }
+  return 0;
+}
+
 DEFUN ("x-select-font", Fx_select_font, Sx_select_font, 0, 2, 0,
        doc: /* Read a font name using a W32 font selection dialog.
 Return fontconfig style font string corresponding to the selection.
@@ -2527,7 +2545,8 @@ in the font selection dialog. */)
 
   cf.lStructSize = sizeof (cf);
   cf.hwndOwner = FRAME_W32_WINDOW (f);
-  cf.Flags = CF_FORCEFONTEXIST | CF_SCREENFONTS | CF_NOVERTFONTS;
+  cf.Flags = CF_FORCEFONTEXIST | CF_SCREENFONTS | CF_NOVERTFONTS | CF_ENABLEHOOK;
+  cf.lpfnHook = font_dialog_callback;
 
   /* If exclude_proportional is non-nil, limit the selection to
      monospaced fonts.  */