diff --git a/sdl-game-controller.cc b/sdl-game-controller.cc
index 8849aed..e1262a9 100644
--- a/sdl-game-controller.cc
+++ b/sdl-game-controller.cc
@@ -19,14 +19,14 @@ static struct
     GLint color;
     GLint position;
 } uniforms;
-int color = 0;
+unsigned int color = 0u;
 GLfloat size = 0.2;
 GLfloat position[2] = {0.0, 0.0};
 GLfloat colors[][4] = {
     {1.0, 0.7, 0.0, 1.0},
-    {0.0, 0.5, 1.0, 1.0},
+    {0.0, 0.2, 1.0, 1.0},
     {1.0, 1.0, 0.0, 1.0},
-    {0.2, 0.2, 1.0, 1.0},
+    {0.2, 1.0, 1.0, 1.0},
 };
 float movement[2];
 static SDL_Event UpdateEvent;
@@ -194,9 +194,23 @@ int main(int argc, char *argv[])
                         movement[1] = 0.0;
                 }
             }
-            else if (event.type == SDL_CONTROLLERBUTTONDOWN)
+            else if ((event.type == SDL_CONTROLLERBUTTONDOWN) &&
+                     (event.cbutton.state == SDL_PRESSED))
             {
-                std::cerr << "button!" << std::endl;
+                switch (event.cbutton.button)
+                {
+                case SDL_CONTROLLER_BUTTON_A:
+                    size *= 0.8;
+                    break;
+                case SDL_CONTROLLER_BUTTON_B:
+                    size *= 1.2;
+                    break;
+                case SDL_CONTROLLER_BUTTON_X:
+                    color++;
+                    if (color >= sizeof(colors) / sizeof(colors[0]))
+                        color = 0u;
+                    break;
+                }
             }
             else if (event.type == SDL_USEREVENT)
             {