How to avoid blinking iframe?

@arnoldo.moen 

To avoid a blinking iframe, you can try the following solutions:

1. Set the iframe's CSS display property to "none" initially, and then set it to "block" or "inline" once the content has finished loading.
2. Use the HTML5 sandbox attribute to restrict the iframe's behavior and prevent it from flashing while loading.
3. Preload the content of the iframe using AJAX or other techniques so that it is immediately available when the iframe is displayed.
4. Optimize the content being loaded in the iframe to reduce loading time and prevent flashing.
5. Use a loading spinner or animation to indicate that the content is loading and to distract from any flashing that may occur.