To see the difference between old and new themes, check out the first screenshot below, which shows a Nemo file browser window with the Mint-Y theme as it was in Mint 19 (on the left), and using the Mint-Y theme with changes in 19.1 (on the right): https://arstechnica.com/gadgets/2019/01/linux-mint-19-1-a-sneaky-popular-distro-skips-upheaval-offers-small-upgrades/
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