[Usability] UI design question

["Dave Foster" <dave foster gmail com>]

Hi, 

I'm crossposting to both the usability list and gtk app devel list, i hope this is ok, as I couldn't really see where my question fit in.  I am designing a gtk application and I'm trying to follow the HIG, and I wanted to get some opinions on a "simple" dialog in the application.  Here is a description (chopped out of an email i sent to a friend earlier):

I've come up with 5 distinct actions this dialog 
should have.  The actions are as follows:
- Create a new theme
- Create a new theme based on an existing theme
- Open an existing theme
- Edit current theme
- Open last edited theme

(the last two items will have text inserted at run time to explain what 
those theme names are)

I thought the best way to do this was a radio button group, as it would 
show all the available actions neatly on one screen.  The problem is, 
there is additional information that needs to be taken in depending on 
what is selected.  For the top two items (both creates), a theme name 
must be given in a text box.  For the create new based on existing and 
open existing, a theme needs to be selected from a list of themes.

Because of these additional controls, I don't know how to lay this 
dialog out so that the user can see that the listbox and textbox are 
dependant on selections in the radio group. 


Another idea is to use a drop down, which could be put above the 
textbox/listbox, and have those go sensitive/insensitive as appropriate, 
but i feel that masks the user from seeing the possibilities of 
opening/creating themes.

Yet one more idea is to use a multiple screen approach, with simple 
buttons that have nice icons that indiciate which action to take, and have a second 
dialog then ask for the required information such as a name or existing 
theme, but i feel multiple screens is a bit wizardy and not needed.

Any thoughts?  thanks all.
dave