[FR] Adding gcode before/after "preheat"

[ilko-k]

Is your feature request related to a problem? Please describe.

Preheating only does its purpose and nothing else, just heat and standby.

Are you looking for hardware support?

No.

Describe the feature you want

Ability to include gcode before and after a "preheat" action in order to customize an event, like a simple sound or more complicated macros.

Additional context

Everyone could benefit of this feature but more particularly, the LVGL UI (aka MKS UI) since it shows only two preheat definitions in the preheat menu. Also, there is a limit of only 6 custom macros so each slot must be occupied smartly, thus restricting possibilites.

[rondlh]

I guess you can use EXTENSIBLE_UI for this purpose