Description of problem:
When creating a new VM with virt-manager, and selecting managed storage to have finer control over how the volume is created, the user interface does not make it very easy to create a new volume.


Version-Release number of selected component (if applicable):
$ virt-manager --version
0.8.3

How reproducible:
Always


Steps to Reproduce:
1. Start virt-manager, and start to create a new virtual machine.  Use the name 'name' (other details, like installation image and OS type are not relevant, but enter something so as to get to step 4)
2. On step 4 of 5, switch the radio button to 'Select managed or other existing storage', then click Browse
3. Select a pool, then click 'New Volume'
4. In the Name field, delete the final 'g' then retype it
5. Click 'Finish'.
6. Hit 'Cancel' to exit the storage manager, and 'Cancel' to exit the VM creation.  Back in the VM Manger, hit Edit->Host Details, and select the Storage tab.
7. Select the just-created name.img.img, and hit 'Delete Volume'
8. Hit 'New Volume', and type in something in the Name: field.

  
Actual results:
At item 3, notice that Name is filled in with a default value (name.img), but the Finish button is grayed out.
At item 5, notice that the volume was created with the name 'name.img.img'.
Contrast that with item 8, where the Name: field starts blank, and Finish is grayed out until a name is entered.

Expected results:
In step 3, since the name is already going to have .img appended by the creation, it would make more sense to pre-populate the Name: field with 'name' instead of 'name.img'.
In step 3, since the pre-populated name is already valid, it doesn't make sense to keep the 'Finish' button grayed out; a user should be able to click through without any typing if the default name was good enough.
The sequence in step 8 is a bit more user-friendly - a name must be entered to proceed, so Finish is grayed out as long as Name: is blank (and goes gray again if Name: is cleared).


Additional info: