Running Debian tracking testing with Mate/Xfce and smplayer_16.6.0-3.1_amd64. This version (and all qt5 versions so far) use a very basic "Open Dialog" window. On the left side it is only showing one bookmark: Computer, instead of using an existing bookmark file. It is possible to add bookmarks however. Also, the window does not remember it's size or position.
On Linux Mint 17.3 the "Open Dialog" window is what I expect.
No big deal. Just thought I'd mention it.