There seems to be some inconsistencies in both the "Open" and the "Save" file dialogs, and at least one weird bug.
The Open dialog:
The Open dialog shows a checkbox to "Show hidden files". You can use either this checkbox, or else you can right-click in the main pane to show/hide hidden files. One small issue I notice is that when I use the right-click method of changing the hidden-file view, the lower checkbox does not get updated until I click in the main pane. Not a big deal at all, and everything else here works, but I thought I'd mention it.
The Save dialog:
The Save dialog differs from the Open dialog. It has a checkbox in the dialog for "Open file in new tab", which doesn't seem to apply here (since we're saving a file, not opening one). Checking this checkbox grays out the "Rename" button (it's not entirely obvious to me why there's a Rename button in the save dialog ... if I wanted to rename the file, I'd use "File --> Save as", no?).
The Save dialog (bigger bug):
If I create a new file (Ctrl-N), type a few characters (or not), then go to save it (Ctrl-S), in that save dialog, if I then right-click to show/hide hidden files, toggling it on and off then shows me *only* files and directories starting with a dot (opposite of what's expected). This bug only happens when the dialog starts of showing me hidden files (that is, if I previously had told it to show me hidden files).
---John