If I want to use dev16 and so I have to use compiler version 1.4.0-rc, how I can use the preview if until Canary 8 ?

I tried and gave up, I think all my dependencies broke when updating compiler version

Check my setup here. This seems to be working fine for me - https://github.com/vinaygaba/Learn-Jetpack-Compose-By-Example/blob/master/app/build.gradle

I'm glad that work fine for you, but your same project, on my android studio (v 4.2, canary 7) doesn't show the preview.

Yeah known issue - https://kotlinlang.slack.com/archives/CJLTWPH7S/p1595516337213000