Like in Gedit's quickopen plugin, in addition to recent files,
some sources for searching files are added :

  - home's directory
  - desktop's directory
  - local bookmark directories
  - Gedit file browser directory
  - Gedit's active document directory
  - currently opened documents in the corresponding Gedit's window

The file list shown is always sorted by
he most recently used files at top.

By default, ie with no text in the search entry,
the recent files list is shown, limited in size by the Gedit's gsetting:
  path: org.gnome.gedit.preferences.ui and key: max-recents

With text in the search entry, the filtering is done with no limit
amongst all the sources ( ie the recent files's source is not limited )

Searches are only done in local/native directories, except
with the recent file list if you have opened distant files.

The treeview is also limited in height by the same max-recents settings:
the treeview show max-recents entries but no more than ten, the scrollbar
taking the relay.

You can directly hit enter to validate a file name / uri
in the search entry. The recognized cases are:

  - an uri
  - a local file name:
    the prefix ~/ is replaced by your home's dir if present.

All file's queries for lists's computation are done asynchronously.

You can print debug and timing by setting #if 1 in place of #if 0
in gedit-open-document-selector-helper.h, then rebuild.

You can get more informations at the top of this file:
gedit-open-document-selector-store.c

https://bugzilla.gnome.org/show_bug.cgi?id=742280