Create font_button.rb

First standalone addition of font_button - currently misses 3 components.

examples2/font_button.rb

@@ -0,0 +1,37 @@
+# ============================================================================ #
+# This example (font_button.rb) shall demonstrate the following
+# functionality (5 components), as well as their implementation-status
+# in regards to this file:
+#
+#   :new_font_button              # [DONE]
+#   :font_button_font             # [NOT YET ADDED]
+#   :font_button_on_changed       # [DONE]
+#   :free_font_button_font        # [NOT YET ADDED]
+#   :free_font_descriptor         #[NOT YET ADDED]
+#
+# Unsure what ":load_control_ font" is.
+# ============================================================================ #
+require 'libui'
+LibUI.init # Initialize LibUI.
+
+main_window = LibUI.new_window('font_button.rb', 640, 240, 1)
+
+vbox = LibUI.new_vertical_box
+LibUI.box_set_padded(vbox, 1)
+_ = LibUI.new_font_button # Create a new font-button here.
+LibUI.box_append(vbox, _, 0) # Add the font-button here.
+
+LibUI.font_button_on_changed(_) {|entry|
+  puts 'The font was changed. (class '+entry.class.to_s+')'
+}
+
+LibUI.window_set_child(main_window, vbox)
+LibUI.control_show(main_window)
+
+LibUI.window_on_closing(main_window) {
+  LibUI.quit
+  1
+}
+
+LibUI.main
+LibUI.uninit