Feature request: exclude buffers in certain modes

[Tyler Smith]

I notice when one of my windows is visiting a pdf file in PDFView mode, ace-jump becomes really slow. I suspect because it searches the source text of the pdf, which may be extremely long relative to the displayed text. It would be very nice if we could exclude buffers in certain modes from being searched by ace-jump.

I know I can set ace-jump-mode-scope. However, in my current use case, I am jumping back and forth between two windows, while reading a pdf in the third. So I'd like something between 'global and 'window.

Thanks!