The first thing that comes to mind: why don’t you let the choice of “how to interpret the format” to a second step? A bit like Excel, when it imports documents from another format.
Benefits of using a second step:
- the Open dialog is not crowded with options; no need for user to make decision until it is really required
- you have space to show all the options via buttons, selectable with a single click. So the user knows what her/his choices are. (Plus, drop down requires two clicks)
- buttons have bigger area to click on => by Fitts’ Law, it’s easier to click on them.
(But make sure the controls can also be selected via Tab on the keyboard, not just via mouse)
Also, do you need to show the path for every file? What about letting the user navigate to a folder and listing the files inside that folder only? (Bonus points if you make it usable via keyboard only, like Mac Finder)
Ask you users – or observe them – to find what their hierarchy is; maybe instead of filesystem folders they would prefer a hierarchy based on choosing the currency first, then Name, and then see the list of files for those two filters? Or, make the Open dialog based on filters for Currency, Period, name etc. and then show the files matching those filters regardless of where they are in the filesystem.
Your title says “Select A data file”, but your image shows TWO data files being selected. If that is a multiselect open, then you should reword the title to “Select file(s) to open” or sth similar. You don’t even need to use the word “file” – instead use whatever name your users have for these data collections. And, always respect the conventions of the OS for selecting multiple files, i.e. ctrl-clicking, shift-clicking, click-and-dragging etc.
Last point: What is the difference between Back and Cancel?