diff --git a/v5/desktop.py b/v5/desktop.py
index efd21bb..4c8b9ad 100644
--- a/v5/desktop.py
+++ b/v5/desktop.py
@@ -50,3 +50,45 @@ def desktop_createSelectedTiles(p):
     tile.visible = False
   #}
 #}
+
+# Hide deselected tile and show selected one
+#
+# Conditions:
+# 1. tile has just been selected
+def desktop_displaySelectedTile(p):
+  if (
+    p.c.recentField == "selectedId"
+  ):
+    id = p.c.selectedId
+    p.deselectedTiles[id].visible = False
+    p.selectedTiles[id].visible = True
+  #}
+#}
+
+# Postpone hiding of matching tiles for better UX
+#
+# Conditions:
+# 1. a pair of tiles has been matched
+def desktop_scheduleHidingOfMatchingTiles(p):
+  if (
+    p.c.recentField == "hiddenItems"
+  ):
+    p.sequentialTimer.schedule("hideMatchingTiles", True, 500)
+  #}
+#}
+
+# Hide matching tiles
+# TODO: Rearrange the position of the func
+#
+# Conditions:
+# 1. ...
+#def desktop_hideMatchingTiles(p):
+#  if (
+#    p.c.recentField == "hiddenItems"
+#  ):
+#    for id in p.c.hiddenItems:
+#      p.deselectedTiles[id].visible = False
+#      p.selectedTiles[id].visible = False
+#    #}
+#  #}
+##}
diff --git a/v5/desktop_Platform.py b/v5/desktop_Platform.py
index e4f6143..ab81b5a 100644
--- a/v5/desktop_Platform.py
+++ b/v5/desktop_Platform.py
@@ -7,5 +7,6 @@ class desktop_Platform:
     self.deselectedTiles = []
     self.mousePosition = []
     self.selectedTiles = []
+    self.sequentialTimer = None
     self.sprites = arcade.SpriteList()
     self.textures = []
diff --git a/v5/desktop_SequentialTimer.py b/v5/desktop_SequentialTimer.py
new file mode 100644
index 0000000..9a5eb02
--- /dev/null
+++ b/v5/desktop_SequentialTimer.py
@@ -0,0 +1,10 @@
+class desktop_SequentialTimer():
+  def __init__(self):
+    self.queue = []
+
+  def update(self):
+    pass
+
+  def schedule(self, key, value, timeout):
+    pass
+  
diff --git a/v5/desktop_aux.py b/v5/desktop_aux.py
index 17bbe97..83d9ad9 100644
--- a/v5/desktop_aux.py
+++ b/v5/desktop_aux.py
@@ -1,10 +1,11 @@
 import arcade
 
-# Find tile id at the specified location
+# Find a visible tile id at the specified location
 def desktop_aux_tileIdAt(p, x, y):
   sprites = arcade.get_sprites_at_point([x, y], p.sprites)
   if (
-    len(sprites) != 0
+    len(sprites) != 0 and
+    sprites[0].visible
   ):
     return sprites[0].guid
   #}
diff --git a/v5/main-gui.py b/v5/main-gui.py
index 310776a..08cd009 100644
--- a/v5/main-gui.py
+++ b/v5/main-gui.py
@@ -5,6 +5,7 @@ from ctx import *
 from ctx_test2 import *
 from desktop import *
 from desktop_Platform import *
+from desktop_SequentialTimer import *
 from desktop_Window import *
 from gui import *
 from gui_aux_test import *
@@ -81,13 +82,16 @@ ctrl.registerCallback(printOutput)
 ctrl.registerFieldCallback("exit", lambda c: sys.exit(0))
 
 p = desktop_Platform()
-# Keep copy of ctrl in platform, too.
 p.ctrl = ctrl
+p.sequentialTimer = desktop_SequentialTimer()
 
 # Copy context to platform.
-def copyContext(c):
+# And process lots of functions that are interested in changes.
+def process(c):
   p.c = c
-ctrl.registerCallback(copyContext)
+  desktop_displaySelectedTile(p)
+  desktop_scheduleHidingOfMatchingTiles(p)
+ctrl.registerCallback(process)
 
 ctrl.set("didLaunch", True)
 ctrl.set("playfieldSize", 2)
diff --git a/v5/memory_Context.py b/v5/memory_Context.py
index db806cc..982c874 100644
--- a/v5/memory_Context.py
+++ b/v5/memory_Context.py
@@ -4,6 +4,7 @@ class memory_Context:
     self.didLaunch = False
     self.exit = False
     self.hiddenItems = []
+    self.hideMatchingTiles = False
     self.input = ""
     self.mismatchedItems = []
     self.outputGoOn = ""