Index: tests/TestMain.h
==================================================================
--- tests/TestMain.h
+++ tests/TestMain.h
@@ -32,7 +32,9 @@
 	of_point_t position;
 	of_dimension_t scale;
 	BOOL running;
 	ogk_rotation_t rotation;
 	ogk_color_t tint;
+	OFThread *animationThread;
+	BOOL stopAnimation;
 }
 @end

Index: tests/TestMain.m
==================================================================
--- tests/TestMain.m
+++ tests/TestMain.m
@@ -21,10 +21,16 @@
 #import "OGKDisplay.h"
 #import "OGKEvent.h"
 #import "OGKEventQueue.h"
 #import "OGKBitmap.h"
 #import "TestMain.h"
+
+@interface TestMain ()
+- (void)draw;
+- (void)handleEvents;
+- (void)toggleAnimation;
+@end
 
 OF_APPLICATION_DELEGATE(TestMain)
 
 @implementation TestMain
 - (void)display: (OGKDisplay*)display
@@ -68,10 +74,13 @@
 		rotation.angle -= M_PI / 128;
 		break;
 	case OGK_KEY_RIGHT:
 		rotation.angle += M_PI / 128;
 		break;
+	case OGK_KEY_A:
+		[self toggleAnimation];
+		break;
 	case OGK_KEY_Q:
 		running = NO;
 		break;
 	}
 }
@@ -112,17 +121,46 @@
 	[eventQueue handleEvents];
 }
 
 - (void)draw
 {
+	ogk_rotation_t localRotation;
+	@synchronized (self) {
+		localRotation = rotation;
+	}
+
 	[OGKBitmap clearToColor: OGK_COLOR_BLACK];
 	[bitmap drawAtPosition: position
 			 scale: scale
-		      rotation: rotation
+		      rotation: localRotation
 			  tint: tint];
 	[display update];
 }
+
+- (void)toggleAnimation
+{
+	@synchronized (self) {
+		if (animationThread != nil) {
+			stopAnimation = YES;
+			[animationThread join];
+			animationThread = nil;
+			stopAnimation = NO;
+			return;
+		}
+
+		animationThread = [OFThread threadWithBlock: ^ (id object) {
+			while (!stopAnimation) {
+				@synchronized (self) {
+					rotation.angle -= M_PI / 256;
+				}
+				[OFThread sleepForTimeInterval: 0.01];
+			}
+			return nil;
+		}];
+		[animationThread start];
+	}
+}
 
 - (void)applicationDidFinishLaunching
 {
 	ogk_display_flags_t flags =
 	    OGK_DISPLAY_FLAGS_RESIZABLE |