I decided to play with GtkSourceView for a while and I started with this as base code.
I noticed that after an auto-complete window pops up, it doesn't filter or even select proposals that match what I've written since it popped up. I tried implementing gtk_source_completion_provider_get_start_iter() because I thought that if it knows where my completion start it can filter automatically, but it doesn't. It just knows where to start replacement when proposal is activated. While reading the API documentation I expected to find something like gtk_source_completion_proposal_match() similar to the way it deal with filtering providers. Changing the selection while I type will also be great but I couldn't find a way to change selection in the auto completion box.
So, is filtering proposals as you type even supported by GtkSourceCompletion? And if so, how do I enable it?
Maybe I should build a new provider for each completion and filter manually? this doesn't sound like the right way but I think it beats writing my own implementation of a completion widget.