[gtkmm] Documentation: Explain key values

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 80c95e45089b99933263cdb681ebf4074d3d654d
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Tue Oct 6 13:04:12 2020 +0200

    Documentation: Explain key values
    
    and add links to gdk/gdkkeysyms.h. Fixes #6

 gdk/src/event.hg              |  5 +++++
 gtk/gtkmm/accelerator.h       |  5 +++++
 gtk/gtkmm/accelkey.h          |  7 ++++++-
 gtk/src/cellrendereraccel.hg  |  5 +++++
 gtk/src/eventcontrollerkey.hg |  5 +++++
 gtk/src/label.hg              |  5 +++++
 gtk/src/shortcuttrigger.hg    | 10 ++++++++++
 7 files changed, 41 insertions(+), 1 deletion(-)
---
diff --git a/gdk/src/event.hg b/gdk/src/event.hg
index f3a9f773..980576fa 100644
--- a/gdk/src/event.hg
+++ b/gdk/src/event.hg
@@ -57,6 +57,11 @@ struct EventSequence;
  * In GTK applications the events are handled automatically by toplevel
  * widgets and passed on to the event controllers of appropriate widgets,
  * so these functions are rarely needed.
+ *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
  */
 class GDKMM_API Event final
 {
diff --git a/gtk/gtkmm/accelerator.h b/gtk/gtkmm/accelerator.h
index 6cd1afca..bea2d96b 100644
--- a/gtk/gtkmm/accelerator.h
+++ b/gtk/gtkmm/accelerator.h
@@ -35,6 +35,11 @@ namespace Gtk
  * If you want to set up keyboard accelerators for widgets,
  * Gtk::ShortcutTrigger is probably more convenient than the
  * functions in this namespace.
+ *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
  */
 namespace Accelerator
 {
diff --git a/gtk/gtkmm/accelkey.h b/gtk/gtkmm/accelkey.h
index 95a14225..f3b8e51e 100644
--- a/gtk/gtkmm/accelkey.h
+++ b/gtk/gtkmm/accelkey.h
@@ -33,7 +33,12 @@ namespace Gtk
  * By defining accelerator paths you can allow the user of your application
  * to change accelerators himself. An example of an accelerator might be
  * "<MainWindow>/File/Open". Modified accelerators may be saved.
- * @see Gtk::AccelMap
+ *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
+ *
  * @ingroup Menus
  */
 class GTKMM_API AccelKey
diff --git a/gtk/src/cellrendereraccel.hg b/gtk/src/cellrendereraccel.hg
index 78e561bf..d587bb82 100644
--- a/gtk/src/cellrendereraccel.hg
+++ b/gtk/src/cellrendereraccel.hg
@@ -34,6 +34,11 @@ namespace Gtk
  * If the cell renderer is editable, the accelerator can be changed by
  * simply typing the new combination.
  *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
+ *
  * @ingroup TreeView
  * @newin{2,10}
  */
diff --git a/gtk/src/eventcontrollerkey.hg b/gtk/src/eventcontrollerkey.hg
index 792e6083..d5745bf8 100644
--- a/gtk/src/eventcontrollerkey.hg
+++ b/gtk/src/eventcontrollerkey.hg
@@ -30,6 +30,11 @@ class GTKMM_API Widget;
  * %Gtk::EventControllerKey is an event controller meant for situations
  * where you need access to key events.
  *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
+ *
  * @newin{3,94}
  *
  * @ingroup Gestures
diff --git a/gtk/src/label.hg b/gtk/src/label.hg
index 43cef67f..a27ac686 100644
--- a/gtk/src/label.hg
+++ b/gtk/src/label.hg
@@ -32,6 +32,11 @@ class GTKMM_API Menu;
  *
  * A simple setable widget for holding a Glib::ustring.
  *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
+ *
  * The Label widget looks like this:
  * @image html label1.png
  *
diff --git a/gtk/src/shortcuttrigger.hg b/gtk/src/shortcuttrigger.hg
index 9c3bcdfe..fda0e90c 100644
--- a/gtk/src/shortcuttrigger.hg
+++ b/gtk/src/shortcuttrigger.hg
@@ -100,6 +100,11 @@ public:
 
 /** A Gtk::ShortcutTrigger that triggers when a specific keyval
  * and (optionally) modifiers are pressed.
+ *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
  */
 class GTKMM_API KeyvalTrigger : public ShortcutTrigger
 {
@@ -118,6 +123,11 @@ public:
 };
 
 /** A Gtk::ShortcutTrigger that triggers when a specific mnemonic is pressed.
+ *
+ * Key values are the codes which are sent whenever a key is pressed or released.
+ * The complete list of key values can be found in the
+ * <a href="https://gitlab.gnome.org/GNOME/gtk/tree/master/gdk/gdkkeysyms.h";>gdk/gdkkeysyms.h</a>
+ * header file. They are prefixed with <tt>GDK_KEY_</tt>.
  */
 class GTKMM_API MnemonicTrigger : public ShortcutTrigger
 {