Missing features that would be important (some elements, shorturl, collaborative editing)

Hi Fábio!

Let me address your concerns one by one. For any item below that contains a link to a corresponding public feature request, you are welcome to vote for it, which will subscribe you to issue updates and provide feedback for us regarding the importance of these features.

1. Collaborative editing. As mentioned in the other thread, you are welcome to vote here (which I can see you've already done, but will leave it here for others to see as well): JT-58295.
2. Diagrams from diagrams.net can be embedded in articles. More embedding will be possible once we add support for widgets in articles: JT-68304.
3. Short URL: can you provide more information on the use case?
4. Losing the session: this should be covered by collaborative editing whenever it is released, since changes will need to be saved on the go. Not sure about the need for logging back in, can you share more details about this experience?

Could you also elaborate on the "hide" and "text/info/tip" elements? You can read more about the Rich Text editor here. CommonMark spec is supported for Markdown, and you can learn more about the syntax here. It is possible that some of what you require can be implemented this way.