This drives me f'n nuts, and I'm sure I'm not alone. You know the little hero+item indicator that pops up in the bottom-right of your UI when a teammate purchases/completes an item? It has a higher UI layer (priority) than the tooltip that appears when you mouse over your gold.

This is very significant because I (and you, hopefully, if you're doing things right) frequently mouse-over my gold to see how much of a surplus I have, or to see how much unreliable gold I have (so I can keep in the back of my mind how much I need to panic-buy before death). But if that ally item popup is in the way I have to wait several seconds for that to disappear before I can see my goddamn gold tooltip, even if I bring up the gold tooltip AFTER the allied item acquisition popup. Ergo, it's a layer issue and not a sequence issue.