Toast Messages Overlap Each Other

**I'm submitting a ...** (check one with "x")
[x ] bug report
[ ] feature request

**Current behavior:**
When a toast message is displayed, it stays on screen for a period of time and then goes away. If a second toast message is produced before it disappears, it will overlap the first, even if there was not enough time to read the first toast (or even notice it appear).

**Expected behavior:**
The subsequent toast messages would either a) stack up vertically, as in other usages or b) queue up to be displayed one-by-one, like android toasts

**Steps to reproduce:**
1. Send a Toast.
2. Immediately send another Toast.