The problem on my mac is that I can't look at any other window, e.g. my webbrowser, as the 'active' window, i.e. the one on top, without plant tycoon pausing. Whether I'm in the nursery waiting for plants to sell or the greenhouse for plants to grow.

I don't even see an option to have two windows going at the same time for different plant tycoon games.

Regarding the first issue though, this isn't something I've noticed before, so I wondered if it was to do with this particular mac version of the game, rather than something about macs in particular? Not a tech expert and happy to learn, and/or be corrected!