leptos 0.7 version of Callback

[luoxiaozero]

Is your feature request related to a problem? Please describe.

Warning and conversion problems.

Related issue: #2041 #2142

Related PR: #1921

Describe the solution you'd like

1. Remove it in leptos 0.7.
2. Rewrite. (Ensure consistency in stable and nightly.)

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[gbj]

Is there a reason you're opening a separate issue in addition to #2041 and #2142?

[luoxiaozero]

What I want more to know is how to solve Callback-related issues in leptos0.7. (perhaps it would be more appropriate to turn this into a discussion)

[gbj]

Okay. I'm going to add the 0.7 milestone to those other two issues, and close this one so that we can keep the conversation in one place.

Baptiste's comment here is the closest I've seen to a solution so far.