[Feature Request] Show the effects live in a preview window or directly in the canvas

[raindropsfromsky]

Is your feature request related to a problem? Please describe.
Currently, the user has to set the parameters of effects such as "obfuscate" without knowing how it will turn out.
The effect is seen only after applying.

But there is a problem: When there are two or more parameters to be set, the end-result is not predictable.
If the user does not like the end-result, he has to undo the effect and try again.
At that time, he has to try a different combination of the parameters.
As a result, he has not learned anything from the previous attempts.
Thus, the "trial-and-error" method is too tedious.

Describe the solution you'd like
Let the user see a live preview.
This can be provided right in the canvas.
Alternatively, provide the preview in a separate Preview window.

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.