latest Yosemite update

I ran the latest Yosemite update (2016-004) 3 days ago and now both Firefox and Safari are acting differently. If I for example have mail open on the desktop and then I open either Firefox or Safari, mail disappears from the screen. I have to reopen mail either from the dock or mission control. If I have mail open on the desktop and I open another app other than F or S, mail stays on the desktop. I must admit both F and S open faster.

I also updated El Capitan on my mbp and it is not closing apps when Firefox or Safari is opened.
Anybody else experiencing this?

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