Better drop-downs for filter buttons

[FenPhoenix]

Currently, we have a few filter buttons that require drop-downs so the user can enter more information (these are the two date filter buttons and the rating filter button). Right now, these drop-downs are just separate windows with OK and Cancel buttons. This is functional enough but looks hacky, and autosizing based on localized strings (particularly the title bar string) is difficult (and isn't currently done). At this point we have a global mouse hook system in place, so we can dig out the old custom drop-down tests and convert them to use the global mouse hook so they can function correctly and without glitches or corner cases. We then won't have or need a title bar at all, and we can get rid of the side-by-side OK and Cancel buttons too, and then autosizing will be easy.

• Implement autosize-width
• Make windows into some kind of dropdowns instead