+- (void) _setViewportWidthOnMainThread:(NSNumber *)width {
+ [self setViewportWidth:[width floatValue]];
+}
+
+- (void) setViewportWidthOnMainThread:(float)width {
+ [self performSelectorOnMainThread:@selector(_setViewportWidthOnMainThread:) withObject:[NSNumber numberWithFloat:width] waitUntilDone:NO];
+}
+