The order in which objects should be drawn to display correctly. (noun)
A property of a graphical object that indicates its position in the z-order. (noun)
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Use "z-order" in a sentence
"Or if i know the window is 1 layer down in the z-order, i use a single alt tab to bring it to front and a single alt tab again to get back."
"Fundamentally, that layout system involves absolute x and y coordinate pairs, and an explicit or implicit z-order."
"• Manage Every File on Your Hard Drive AltTabIt! enhances your task switching experience by showing screenshots of all running windows, sorting window lists by name, title, or z-order, and launching pre-selected apps and files."