Insert plain commands into the document with an Inset

[Daniel]

On 2022-04-10 08:07, Daniel via lyx-users wrote:
> 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

ps. There are separate GUI features for \pagestyle 
(https://www.lyx.org/trac/ticket/12394) and \mainmatter 
(https://www.lyx.org/trac/ticket/12424) on the way. But since I lack at 
least the abilities to finish those patches for backwards compatibility, 
I am not sure whether they will appear in LyX any time soon.