Nextion Erase individual primitives? Changing size of crop?

Two questions in one.

Is there a way to change the size of a crop programmatically? I try sending something like qRT0.h=20 but it returns "Parse Assignment operation failed" so I assume the answer is no. Just asking if there is another way.

My other option is to use primitives as I can generate them with sizes I need dynamically. That would work, but is there a way to delete specific primitives? Or once they are drawn you have to redraw the whole page to erase?

Thanks!

Is there a way to change the size of a crop programmatically? I try sending something like qRT0.h=20 but it returns "Parse Assignment operation failed" so I assume the answer is no. Just asking if there is another way.

I tried:

SS3.hig=100

On one of mine and it changed the height. My understanding is that those things shown in green in the Nextion editor can be changed by Nextion instructions, those in black cannot. h is one of the ones in black and I would not expect to be able to change it.

My other option is to use primitives as I can generate them with sizes I need dynamically. That would work, but is there a way to delete specific primitives? Or once they are drawn you have to redraw the whole page to erase?

By primitives I think you mean draw objects yourself, is that correct? It's ages since I played with that, I think you can delete them or re-draw the background or something but I can't remember how, you will have to experiment, unless someone else comes along who knows.