No way to disable "underline" entirely

[deymundson]

• [x] I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• [x] I have read the documentation and cannot find an answer.

Describe the bug I am attempting to configure the editor to support only a sub-set of possible markdown. One of the features I would like to remove is the ability to underline text. I was able to use the toolbar primitives to create a custom formatting toggle that only includes Bold and Italic buttons, and was able to ensure HTML cannot be used by setting suppressHtmlProcessing={true}, however, it is still possible to underline text by selecting the text and hitting Ctrl-U. The markdown produced then includes <u>text</u>, even though suppressHtmlProcessing is true.

Expected behavior I'm not entirely sure what the correct fix for this would be... a couple options I can think of would be:

1. Ensure <u></u> cannot be produced when suppressHtmlProcessing is true.
2. Add an options prop to the BoldItalicUnderlineToggles, much like the ListsToggle, and then only enable the keyboard shortcuts for those options selected.

[petyosi]

You can achieve this with your own plugin - you need to register two things, basically:

• An mdast visitor with a higher priority than the default one which "drops" the u tag when encountered
• A high priority Lexical command that handles ctrl/cmd+u and stops the underline formatting

Refer to the docs for more details on the matter.

As a general note: the toolbar is an "accessory"; its contents are by no means hard-bound to the editor capabilities, nor they can enable or restrict certain behavior.

[wouterlemcke]

I need this as well. I've been struggling with it for a day now, but cannot really put the pieces together from the docs. Could you provide me/us with an example?