Asynchronously requests that the provider populates the completion results for context.
For providers that would like to populate a gio.list_model.ListModel while those results are displayed to the user, gtksource.completion_context.CompletionContext.setProposalsForProvider may be used to reduce latency until the user sees results.
a #GtkSourceCompletionContext
a #GCancellable or null
a callback to execute upon completion
Asynchronously requests that the provider populates the completion results for context.
For providers that would like to populate a gio.list_model.ListModel while those results are displayed to the user, gtksource.completion_context.CompletionContext.setProposalsForProvider may be used to reduce latency until the user sees results.