Added mnemonic support for linux

src/dorkbox/systemTray/MenuEntry.java

@@ -99,6 +99,16 @@ interface MenuEntry {
      */
     void setCallback(SystemTrayMenuAction callback);
 
+    /**
+     * Sets a menu entry shortcut key (Mnemonic) so that menu entry can be "selected" via the keyboard while the menu is displayed.
+     *
+     * Mnemonics are case-insensitive, and if the character defined by the mnemonic is found within the text, the first occurrence
+     * of it will be underlined.
+     *
+     * @param key this is the key to set as the mnemonic
+     */
+    void setShortcut(char key);
+
     /**
      * Removes this menu entry from the menu and releases all system resources associated with this menu entry
      */

src/dorkbox/systemTray/linux/GtkEntry.java

@@ -90,6 +90,11 @@ class GtkEntry implements MenuEntry {
         }
     }
 
+    @Override
+    public
+    void setShortcut(final char key) {
+    }
+
     @Override
     public
     String getText() {

src/dorkbox/systemTray/linux/GtkEntryItem.java

@@ -39,12 +39,17 @@ class GtkEntryItem extends GtkEntry implements GCallback {
     // these are necessary BECAUSE GTK menus look funky as hell when there are some menu entries WITH icons and some WITHOUT
     private volatile boolean hasLegitIcon = true;
 
+    // The mnemonic will ONLY show-up once a menu entry is selected. IT WILL NOT show up before then!
+    // AppIndicators will only show if you use the keyboard to navigate
+    // GtkStatusIndicator will show on mouse+keyboard movement
+    private volatile char mnemonicKey = 0;
+
     /**
      * called from inside dispatch thread. ONLY creates the menu item, but DOES NOT attach it!
      * this is a FLOATING reference. See: https://developer.gnome.org/gobject/stable/gobject-The-Base-Object-Type.html#floating-ref
      */
     GtkEntryItem(final GtkMenu parent, final SystemTrayMenuAction callback) {
-        super(parent, Gtk.gtk_image_menu_item_new_with_label(""));
+        super(parent, Gtk.gtk_image_menu_item_new_with_mnemonic(""));
         this.callback = callback;
 
 
@@ -62,6 +67,20 @@ class GtkEntryItem extends GtkEntry implements GCallback {
         }
     }
 
+    @Override
+    public
+    void setShortcut(final char key) {
+        this.mnemonicKey = Character.toLowerCase(key);
+
+        Gtk.dispatch(new Runnable() {
+            @Override
+            public
+            void run() {
+                renderText(getText());
+            }
+        });
+    }
+
     @Override
     public
     void setCallback(final SystemTrayMenuAction callback) {
@@ -118,8 +137,19 @@ class GtkEntryItem extends GtkEntry implements GCallback {
     /**
      * must always be called in the GTK thread
      */
-    void renderText(final String text) {
+    void renderText(String text) {
+        if (this.mnemonicKey != 0) {
+            // they are CASE INSENSITIVE!
+            int i = text.toLowerCase()
+                        .indexOf(this.mnemonicKey);
+
+            if (i >= 0) {
+                text = text.substring(0, i) + "_" + text.substring(i);
+            }
+        }
+
         Gtk.gtk_menu_item_set_label(_native, text);
+
         Gtk.gtk_widget_show_all(_native);
     }
 

src/dorkbox/systemTray/linux/GtkMenu.java

@@ -152,6 +152,12 @@ class GtkMenu extends Menu implements MenuEntry {
         });
     }
 
+    @Override
+    public
+    void setShortcut(final char key) {
+        menuEntry.setShortcut(key);
+    }
+
     @Override
     public
     String getText() {

src/dorkbox/systemTray/linux/jna/Gtk.java

@@ -429,8 +429,8 @@ class Gtk {
     // to create a menu entry WITH an icon.
     public static native Pointer gtk_image_new_from_file(String iconPath);
 
-
-    public static native Pointer gtk_image_menu_item_new_with_label(String label);
+    // uses '_' to define which key is the mnemonic
+    public static native Pointer gtk_image_menu_item_new_with_mnemonic(String label);
 
     public static native void gtk_image_menu_item_set_image(Pointer image_menu_item, Pointer image);