Dialog for custom variables

[mariocup]

Hi,

I want to use custom variables to select different types of flash (intern, extern) etc. In the project properties I add an empty custom variable FLASHTYPE. Is it possible with the project settings to call a dialog for entering the value of the variable?

In the wiki page a saw that conditional statements are also possible in variable expansion, but I did not get it work. Perhaps this could be alternative to see if the variable is empty.