gtk: allow to specify accelerators in a platform-independent way

Introduce <Primary> in accelerator strings, which resolves to
GDK_CONTROL_MASK on X11/Win23, and to GDK_META_MASK on quartz.
Also serialize CONTROL/META as <Primary> depending on the platform.

gtk/gtkaccelgroup.c

@@ -35,7 +35,7 @@
 #include "gtkintl.h"
 #include "gtkmainprivate.h"
 #include "gtkmarshalers.h"
-
+#include "gtkprivate.h"
 
 /**
  * SECTION:gtkaccelgroup
@@ -1152,6 +1152,20 @@ is_hyper (const gchar *string)
           (string[6] == '>'));
 }
 
+static inline gboolean
+is_primary (const gchar *string)
+{
+  return ((string[0] == '<') &&
+	  (string[1] == 'p' || string[1] == 'P') &&
+	  (string[2] == 'r' || string[2] == 'R') &&
+	  (string[3] == 'i' || string[3] == 'I') &&
+	  (string[4] == 'm' || string[4] == 'M') &&
+	  (string[5] == 'a' || string[5] == 'A') &&
+	  (string[6] == 'r' || string[6] == 'R') &&
+	  (string[7] == 'y' || string[7] == 'Y') &&
+	  (string[8] == '>'));
+}
+
 /**
  * gtk_accelerator_parse:
  * @accelerator: string representing an accelerator
@@ -1201,6 +1215,12 @@ gtk_accelerator_parse (const gchar     *accelerator,
               len -= 9;
               mods |= GDK_RELEASE_MASK;
             }
+          else if (len >= 9 && is_primary (accelerator))
+            {
+              accelerator += 9;
+              len -= 9;
+              mods |= GTK_DEFAULT_ACCEL_MOD_MASK;
+            }
           else if (len >= 9 && is_control (accelerator))
             {
               accelerator += 9;
@@ -1314,6 +1334,7 @@ gtk_accelerator_name (guint           accelerator_key,
                       GdkModifierType accelerator_mods)
 {
   static const gchar text_release[] = "<Release>";
+  static const gchar text_primary[] = "<Primary>";
   static const gchar text_shift[] = "<Shift>";
   static const gchar text_control[] = "<Control>";
   static const gchar text_mod1[] = "<Alt>";
@@ -1324,6 +1345,7 @@ gtk_accelerator_name (guint           accelerator_key,
   static const gchar text_meta[] = "<Meta>";
   static const gchar text_super[] = "<Super>";
   static const gchar text_hyper[] = "<Hyper>";
+  GdkModifierType saved_mods;
   guint l;
   gchar *keyval_name;
   gchar *accelerator;
@@ -1334,9 +1356,15 @@ gtk_accelerator_name (guint           accelerator_key,
   if (!keyval_name)
     keyval_name = "";
 
+  saved_mods = accelerator_mods;
   l = 0;
   if (accelerator_mods & GDK_RELEASE_MASK)
     l += sizeof (text_release) - 1;
+  if (accelerator_mods & GTK_DEFAULT_ACCEL_MOD_MASK)
+    {
+      l += sizeof (text_primary) - 1;
+      accelerator_mods &= ~GTK_DEFAULT_ACCEL_MOD_MASK; /* consume the default accel */
+    }
   if (accelerator_mods & GDK_SHIFT_MASK)
     l += sizeof (text_shift) - 1;
   if (accelerator_mods & GDK_CONTROL_MASK)
@@ -1361,6 +1389,7 @@ gtk_accelerator_name (guint           accelerator_key,
 
   accelerator = g_new (gchar, l + 1);
 
+  accelerator_mods = saved_mods;
   l = 0;
   accelerator[l] = 0;
   if (accelerator_mods & GDK_RELEASE_MASK)
@@ -1368,6 +1397,12 @@ gtk_accelerator_name (guint           accelerator_key,
       strcpy (accelerator + l, text_release);
       l += sizeof (text_release) - 1;
     }
+  if (accelerator_mods & GTK_DEFAULT_ACCEL_MOD_MASK)
+    {
+      strcpy (accelerator + l, text_primary);
+      l += sizeof (text_primary) - 1;
+      accelerator_mods &= ~GTK_DEFAULT_ACCEL_MOD_MASK; /* consume the default accel */
+    }
   if (accelerator_mods & GDK_SHIFT_MASK)
     {
       strcpy (accelerator + l, text_shift);