I often use the Split Horizontal.
If I have the documents maximized:
I split a document
go to another document
when I return, the split document has been joined

If I have the documents cascaded on the screen.
I split a document
I split another
I can go between documents and the splits remain.
I can maximize the documents and the splits remain.
If I split additional documents while maximized, and move away, they lose the split BUT the documents I split before maximizing... KEEP their split!!
Is there a way to keep splits?
I could write a macro such as
restore document
horizontal split
maximize document
then could I replace the split horizontal icon with the macro?