And not just syntax highlighting
There are options for that already
This would support autocomplete of user written code in modules & classes across a “project” (basically a directory full of a Xojo text project)
Havent figured out how to expose the Xojo framework from any specific version to it - yet
The biggest problem is that there is no cli compiler wich allows this. Exposing the framework would be a big step cause rebuilding the logic…
The entire dream would be using XoJo in another IDE which has completion like everybody is used to and which is working like persons are used to. It is something people want to have. That is one thing I really enjoy with Java and other languages: working with IntelliJ or Eclipse, Netbeans or VSCode. Sad that this isn’t possible with XoJo. If there would be a hope: do it, make it become true 
Ideally a cmd line compiler would be perfect
But that doesnt exist
So the next best thing is to drive it using the automation solutions they HAVE provided
That does allow a person to use the IDE in ways that are a lot like a cmd line compiler (not exactly the same) but its as close as one can get
I doubt they will ever deliver a cmd line compiler or even have incentive to
The way the compiler & IDE are integrated to behave as one unit makes that very unlikely possibility
The compiler is currently a private plugin the IDE uses
The IDE enforces all the licensing and drives the entire build process
To have a cmd line compiler would require moving license enforcement into that new entity as well as the entire building pipeline so the cmd compiler can set out a complete built app
Is it impossible ? No
Likely to happen ? No
This ladies and gentlemen, the missing cli compiler is the fine difference between an expensive toy and any other professional programming langugage.
For sure that is the difference.