LyX ⇒ Fancy Header in Lyx

[Joe2718]

I have a master lyx file with two children as a simple test situation to help my understanding of Lyx.
When I view the master as a pdf it displays OK.
I decided to add the fancy header package by doing in my master document "Document Settings->Page Layout->fancy.
In the preamble I wrote the single line \lhead{Joe}.
The master document would not display as a pdf, I got the error:Class scrbook Error: undefined old font command \se.

I would appreciate your help.
Thank you,
Joe

[Johannes_B]

fancyhdr used to use font commands that are deprecated for over 20 years. It has been fixed in 2016.

To avoid the message, you have to update package fancyhdr or give the global option enabledeprecatedfontcommands.

[Joe2718]

I added \enabledeprecatedfontcommands to the preamble and I get the error "Undefined Control Sequence"

[Johannes_B]

Global option, no command.
I don't know how to do this with LyX.

[torbjorn t.]

Go to Document --> Settings --> Document Class: add enabledeprecatedfontcommands in the text field marked Custom.

[Johannes_B]

As Ulrike just pointed out, A simple \renewcommand\sf{\normalfont\sffamily} or \DeclareOldFontCommand{\sf}{\normalfont\sffamily}{\mathsf} should work too.

[Joe2718]

Thanks, it worked.
It should have been mention in section 3.4 of the additional features doc.

[scottkosty]

Thanks, it worked.
It should have been mention in section 3.4 of the additional features doc.

If you have any suggestions for improving the documentation, please write to lyx-docs@lists.lyx.org. If you are interested in volunteering to implement the changes yourself, we would appreciate the help! Please get in touch (at that email address) before spending time though.

Note that we've made several improvements related to these font commands for the future LyX 2.3.0 release. If you post a minimal .lyx example file, I can let you know whether this particular issue has been fixed.