This one was reported as resolved, but it’s not. Or maybe some other part of it was fixed. In any case the following bug still remains in preview.
If looping Timer is created in .js file it’s never removed when you save while in preview. Actually more you save, more Timers you have in your project making the preview pretty useless in cases where Timer is used. Like in my project
Here’s simplest test case for you to test:
http://simppa.fi/fuse/TimerBug.rar
(fuse 0.25.1)