[NUI][AT-SPI] Event emission added for button

State changed ATSPI event emision added for highlight
Button. This will allow to read "Toggle button, On" and
"Toggle button, Off" by screen-reader.

diff --git a/src/Tizen.NUI.Components/Controls/Button.cs b/src/Tizen.NUI.Components/Controls/Button.cs
index 96021fb..df811f3 100755 (executable)
--- a/src/Tizen.NUI.Components/Controls/Button.cs
+++ b/src/Tizen.NUI.Components/Controls/Button.cs
@@ -97,6 +97,11 @@ namespace Tizen.NUI.Components
                     {
                         instance.UpdateState();
                     }
+
+                    if (instance.IsHighlighted)
+                    {
+                        instance.EmitAccessibilityStateChangedEvent(AccessibilityState.Checked, newSelected);
+                    }
                 }
             }
         },