gnome-text-editor: make sure to overwrite prefilled filename

the new_file test failed today because it seems g-t-e now pre-
fills a suggested filename, with extension, and pre-selects the
name part but not the extension part. So when we type 'list.md'
we wound up saving the file as 'list.md.md'. I think hitting
ctrl-a should fix this, and not break when run on older versions
of g-t-e if we ever do that.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

tests/applications/gnome-text-editor/new_file.pm

@@ -31,6 +31,9 @@ sub run {
     # Save the newly created file.
     send_key("ctrl-s");
     wait_still_screen(3);
+    # select the entire prefilled name (including extension) to overwrite it
+    send_key("ctrl-a");
+    wait_still_screen(3);
     type_very_safely "list.md";
     send_key("ret");
     # Check that the file has been created