From what I can understand, the Poser manual suggests I can edit existing props by using the Grouping Tool. But I can't figure out how to accomplish trimming clothes.

Basically I just want to know how to trim a pair of long pants so that they are shin length, or make a pair of standard shorts into short-shorts. Morphs haven't been effective for me in this regard, so I want to actually cut the clothing props.

Can someone help out a Poser for Dumbies poster child get started?  Thanks!

A vey easy way is to make a transmap, so that the unwanted parts are not visible?
But go to PhilC's website, he has some very good tutorials and tools for you.

Even if it's a bit off topic at first, but perhaps Dr.Geeps recent tut "Making Models - The right Size" could help you with understanding the grouping tool a bit more. Since the usage of it is very well explained in there.

To be found here:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2839179

This will work with dynamic clothing. I don't know about conforming.

1 Load pants.

2 click group tool.

3 in the group tool window click on "new group"

4 name it what you want to call the prop

5 select the parts of the pants you want to keep

6 click on spawn new prop

note: if the vertisies are not in a straight line your edge won't be either.

Thank you everyone, I'm going to go through those tutorials and test out a cloth room example too.

Is PhilC's scissors a much easier method to use than doing the edits within Poser? It seems to me the transmap might be the easiest method for something that isn't cloth.

PhilC's Clothing Designer bundle makes extensive use of the Grouping tools and the cloth room.  Scissors is a six of one, half dozen of the other.  For some things Scissors is easier and for others it's easier to go into the grouping tool, select the polys you want to get rid of, delete them, spawn a new prop from the altered mesh and save it.

as vilters mentioned, for conforming clothing you are really better off making transmaps.  its very straightforward, requires no knowledge of grouping/conforming/etc, and any tweaks can be done in seconds in an image editor.

if you try 'cutting' or deleting groups, if you remove so much as one vertice youve just nuked all the JCMs/morphs in the clothing. nondestructive clothing morphs are one thing, actually changing the mesh is another entirely - and most of the time its too much work  (although with poser 2012 you can also transfer weight maps from one figure to another/clothing item, so that makes rough conforming pretty painless if youre working with one of the WM figures).

making a transmap is relatively simple. download the free version of UVMapper. use it to create a template from the UVs. open this template in any image editor - photoshop, paintshop, gimp, whatever. make a new layer, flood fill it with black, and paint any areas of the clothing you want to be visible white, leave any you want invisible black. then simply load this into the transparency channel. you can do more than just hide parts of the clothing - you can make tattered clothing, wet clothing, different materials like mesh, etc with transmaps.

for dynamic cloth in the cloth room, trim away. id suggest one of the free modeling apps, since by using it youll take your first steps towards learning how to model. most good dynamic meshes are not quads but are delaunay triangulation, so it wont be a simple matter of area select/delete polys. you may have to use either a boolean subtract, a flatten modifier, or move verts by hand or youll end up with a jagged edge where you cut.
of course you can alternately just use transmaps on dynamic cloth as well.