Insert plain commands into the document with an Inset

[Daniel]

On 2022-04-06 22:57, tush via lyx-users wrote:
> How can I create an Inset that once inserted into the document, adds the 
> following commands to the document?:
> 
> \mainmatter
> \pagestyle{fancy} % new page style
> \newgeometry{ new page layout goes here }
> 
> Of course, I can insert these commands with ERT, but I prefer them to be 
> defined a more GUI friendly object.
> 
> If I create a new flex inset, it either adds an environment 
> (\begin{LatexName }...\end{LatexName ) or a command (\LatexName{...}). I 
> don't need any text (ERT or anything else) to be inserted into this 
> inset. Just to insert those commands into the document.
> 
> The List Of Figures insertion, for example, does something similar, but 
> it has some information such as Placement and Extension that are 
> irrelevant in my case.

First, what is the "new page layout goes here" for? Isn't that text that 
needs to be entered into the inset?

Second, I believe custom command insets without arguments cannot be 
created currently. You could create an inset with an argument whose 
argument does nothing to achieve basically the same thing. So, I guess 
it hasn't been a priority to implement custom non-argument insets. But 
it's really a just missing feature.

Daniel