Iframe code in redactor field breaks matrix block title bar when collapsed

[MoritzLost]

Description

I'm getting a really weird error regarding collapsed matrix blocks. Specifically, I have a matrix block with a redactor field inside. In the redactor field, I need to enter some sample HTML code for an iframe (so I want to display literally <iframe src="..."></iframe> on the page as code). The problem is that when I collapse this block, the interface breaks because the MatrixInput JS somehow finds that iframe and inserts it as HTML into the title bar.

The following screenshots demonstrate the problem:

Note that I entered the escaped HTML (with > & <) manually in the code view, since for some reason redactor parses it as HTML when entered normally.

EDIT: After some more testing, I can confirm this isn't related to Redactor. The problem appears to be related to the escaped HTML entities – if those are entered into a plain text field, the same error occurs.

So in a single text field, this is fine:

<iframe src="https://www.begabungslotse.de/suchformular" width="100%" height="300px" frameborder="0"></iframe>

But entering this causes the error above:

<iframe src="test" width="100%" height="300px" frameborder="0"></iframe>

Steps to reproduce

1. Create a matrix field with a redactor field or plain text field inside it and add it to any entry type.
2. Create an entry of that type, add a matrix block and paste the following code into the text field (if it's a Redactor field, paste into the HTML source view): <iframe src="https://example.com" width="100%" height="300px" frameborder="0"></iframe>
3. (Maybe save the page)
4. Collapse the panel. The interface will break. Using the devtools you can verify that the title bar somehow contains the iframe as a real element.

Additional info

• Craft version: 3.7.16
• PHP version: 8.0
• Database driver & version: MySQL 8
• Plugins & versions: Redactor (2.8.8)

[brandonkelly]

Thanks for reporting that! Just fixed for the next release.

[brandonkelly]

Craft 3.7.17 is out now with that fix.