Displays toast.
Only one toast can be shown at a time; if a toast is already being displayed, either toast or the original toast will be
placed in a queue, depending on the priority of toast. See [property@Toast:priority].
If called on a toast that's already displayed, its timeout will be reset.
If called on a toast currently in the queue, the toast will be bumped forward to be shown as soon as possible.
| this |
a toast overlay |
| toast |
a toast |