Previewing sounds in Dimension Pro

From a newbie:  This seems like it should be a simple basic thing, but for the life of me, I cannot find it discussed anywhere:
 
Is there a way to preview instrument sounds in Dimension Pro like there is in TTS-1, without having to actually load them into a project?  Can you do it with a mouse or computer keyboard?  Or can you do it, and do you NEED to do it with a MIDI keyboard (which I am not currently using)? 
 
I am just trying to find a way to audition the various instruments, going down the list.
 
Thanks.

I can quickly run through the sounds by opening the browser window and using the up/down arrows and enter key on the computer keyboard.  This works well as most of the programs are small...but there can be some delay on larger sample sets (like the grand pianos) as they load into RAM.  There is not any type of preview nor can there be because all of the samples for programs are stored as .wav/.ogg files on disk and must be loaded into memory (it is not a streaming sample player).

I thought techead pretty much nailed the answer for you.  But in re-reading your original post, it seems like you want to audition the synth without having a MIDI keyboard.  So you want to audition the DimPro programs using only a mouse or keyboard?

Techead's answer still applies.  Just make sure you have a MIDI track to drive the synth.  After you select a program (either by double-clicking or by using the up/down arrows and the Enter key), hit the spacebar on your keyboard and your MIDI clip will play through the DimPro program that you've selected.  I do this all the time.  I can audition dozens of DimPro programs in just a couple of minutes.

Thanks, everyone.  Rooftree, that sounds like just the kind of procedure I was looking for.  But for whatever reason, I can't get any sounds out of DimPro.
 
I have a song with a number of MIDI tracks that was imported from another program as a MIDI file.  So I tested by soloing one track (Bass).  I have both TTS-1 and DimPro inserted as softsynths.  When I assign TTS-1 to the output of that track, I get music; when assigned to DimPro, I get nothing.  This is after double-clicking to load an instrument program in DimPro and then either using the space bar or clicking the play button. 
 
Any ideas about what I am missing?

Thanks, Techead, for the reply.  But the cause of the problem was apparently something else entirely, and so simple.  I don't understand why this would be, but I found 8 tracks entitled "TTS-1," even though I had inserted only 2 instances of TTS-1.  They were all the lowest listed tracks so they were not visiible on the screen without my scrolling down, and SOME OF THOSE TRACKS WERE SELECTED AS SOLO.  So, the DimPro track(s) would not play with other tracks being soloed.  Once I clicked off the Solos, then DimPro played!
 
But I did encounter another problem: Some of the instrument programs I loaded resulted in no sounds and an error message coming from Notepad:  ".wav not found or couldn't be loaded."  This was true with all the vocal aahs sounds, and others as well.  In some cases where more than one instrument was part of the program, only one of the instruments would have no sound.
 
So, I have some questions:
1)  What would cause the apparent extra instance tracks of TTS-1 to be listed when I only inserted 2 instances (and each instrument track shows only those 2 ouput choices for TTS-1)?
2)  Why would I get those error messages of DimPro .wav files not found or unable to be loaded, and what can I do about it? 
3)  The DimPro instrument programs come in all different sizes, some long, some short, and, consequently, take different lengths of time to load.  Yet most will play whatever the music is in a track, regardless of their size.   So I'm wondering, is there a different kind of usage where the size of the program results in a difference?
 
Thanks much,
Don