I am not following you 100% here ... what is it that you are getting from your UI? If you are attempting to redirect your install in any way, it won't work that way. Path resolution is accomplished by the CostFinalize action, and until you have resolve the initial paths for your directory structure, you can't effectively change anything.
If you absolutely simply MUST have some of your UI run prior to CostFinalize, then you will need to split your dialog sequence. Call the first dialog in the second set from the InstallExecuteSequence (just as you do WelcomeDlg).
Two things to keep in mind:
1. You can't dynamically change anything in the database. The best you can hope for in that regard is to redefine a property through the use of a Edit control. (Actually, you can make temporary changes, but not persist them.)
2. Exercise extreme caution when defining something in the UI sequence and then attempting to use it in the Execute sequence. In my expreience, if you want to do that kind of thing, don't put default values in the Property Table. If you do, the Execute sequence will fairly consistently use the default rather than the value you entered through the UI. Apparently, the UI and Execute sequences run as parallel threads, and the sharing of information across the thread boundaries is rather ... um ... fuzzy.
Please drop me an email if you would like to get down to specifics on this issue.
(Edited by SteveP at 1:53 pm on June 7, 2001)