Make Gdk::ModifierType#none? work when there's hidden reserved valu…

…es in the flag.

spec/gdk_modifier_spec.cr

@@ -0,0 +1,8 @@
+require "./spec_helper"
+
+describe Gdk::ModifierType do
+  it "can be generated from value with internal data" do
+    flag = Gdk::ModifierType.new(16)
+    flag.none?.should eq(true)
+  end
+end

spec/spec_helper.cr

@@ -1 +1,2 @@
 require "spec"
+require "../src/gtk4"

src/bindings/gdk/binding.yml

@@ -0,0 +1,4 @@
+namespace: Gdk
+version: "4.0"
+include:
+  - modifier_type.cr

src/bindings/gdk/modifier_type.cr

@@ -0,0 +1,14 @@
+module Gdk
+  enum ModifierType
+    def none?
+      # From GDK docs:
+      #
+      #   Note that GDK may add internal values to events which include reserved values such as
+      #   GDK_MODIFIER_RESERVED_13_MASK. Your code should preserve and ignore them. You can use
+      #   GDK_MODIFIER_MASK to remove all reserved values.
+      #
+      # We need this so `.none?` works as expected when there's hidden values in the enum
+      (value & MODIFIER_MASK).zero?
+    end
+  end
+end