support multiline prompt for 'Show offscreen command line'

Feature Request

It would be nice if the 'Show offscreen command line` feature supported prompts that use multiple lines.

I don't know if the number of lines of the prompt can be detected. If not, one could add a field for the number of lines to show. Alternatively, one could also allow to specify a range (e.g. to only show the command line and not the directory line).

Here's an example using the pure prompt from https://github.com/romkatv/powerlevel10k which will not show the command, but just the directory:

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