When I use YouTrack Wiki syntax, I can use {cut}
like this:
{cut Block title}
Block content
{cut}
This is very useful feature, but Wiki syntax is deprecated and I can't find something similar in YouTrack Markdown syntax.
UPD: I figured out that I can use stacktrace
as language with backticks:
```stacktrace
Header text
Hidden text
```
But it works different (possibly because it was designed to work with Java stacktraces), not preserving leading whitespaces, not highlighting code, etc.
In YouTrack 2019.3 it will be possible to use this (not tested personally yet):
<details>
<summary>Brief summary</summary>
Unnecessary long description
</details>
Implemented in https://youtrack.jetbrains.com/issue/JT-45636