Comment 8 for bug 135388

If i click on Elite Syncopations (1902) It opens in totem since i have that set as default (and it plays)
Here is output of apt-cache show

gnomefreak@Development:~$ show timidity
Package: timidity
Priority: optional
Section: universe/sound
Installed-Size: 1564
Maintainer: Ubuntu MOTU Developers <email address hidden>
Original-Maintainer: Joost Yervante Damad <email address hidden>
Architecture: i386
Version: 2.13.2-20ubuntu3
Depends: libasound2 (>> 1.0.18), libaudio2, libaudiofile0 (>= 0.2.3-4), libc6 (>= 2.4), libesd-alsa0 (>= 0.2.35) | libesd0 (>= 0.2.35), libflac8, libice6 (>= 1:1.0.0), libjack0 (>= 0.116.1), libncurses5 (>= 5.6+20071006-3), libogg0 (>= 1.0rc3), libpng12-0 (>= 1.2.13-4), libsm6, libvorbis0a (>= 1.1.2), libvorbisenc2 (>= 1.1.2), libx11-6, libxaw7, libxext6, libxmu6, libxt6, zlib1g (>= 1:1.1.4), lsb-base (>= 3.0-6)
Recommends: freepats
Suggests: pmidi, fluid-soundfont
Filename: pool/universe/t/timidity/timidity_2.13.2-20ubuntu3_i386.deb
Size: 626902
MD5sum: 0feafaac17584ecd0c2c8627ce93d9fc
SHA1: e7db6ad3c229b8f19319db6817c224a96179b629
SHA256: b36947aaac249dd9826ab9c36e7b0410e55b2abdac6edb78a73e3c378dad2371
Description: Software sound renderer (MIDI sequencer, MOD player)
 TiMidity++ is a very high quality software-only MIDI sequencer and MOD player.
 It uses sound fonts (GUS-compatible or SF2-compatible) to render MIDI files,
 which are not included in this package.
 .
   * Plays MIDI files without any external MIDI instruments at all
   * Understands SMF, RCP/R36/G18/G36, MFI, RMI (MIDI)
   * Autodetects and supports GM/GS/XG MIDI
   * Understands MOD, XM, S3M, IT, 699, AMF, DSM, FAR, GDM,
     IMF, MED, MTM, STM, STX, ULT, UNI (MOD)
   * Does MOD to MIDI conversion (including playback)
   * Outputs audio into various audio file formats: WAV, au, AIFF,
     Ogg (Vorbis, FLAC, Speex)
   * Supports NAS, eSound, JACK, ALSA and OSS drivers
   * Uses Gravis Ultrasound compatible patch files and SoundFont2 patch
     files as the voice data for MIDI instruments
   * Supports playing from archives (zip, lzh, tar...) and playing remote
     data from the network
   * Timidity++ can be used as an ALSA sequencer device
Homepage: http://timidity.sourceforge.net/
Bugs: mailto:<email address hidden>
Origin: Ubuntu

I dont see anything there that it will use its Ui to play Midi files. However it does say:
" * Plays MIDI files without any external MIDI instruments at all"
when you click on one of the links it will bring up a dialog box askin gyou to "open with" and "save" Can you than open it with Timidity.
Yes there is a bug filed on the "open with" since it defaults to you $HOME dir.
Also as stated above did you try go to >edit>preferences>applications and select what to use to play it?