All the (code) files of an application are held within a master folder referred to as <homefolder>, subfolders named <xaml> and <images> contain xaml files and images respectively.
A preprocessor takes XAML files which have been edited manually (replacing VS conventions with placeholders) is used to substitute useable values as XAML is read and before it is used to create GUI objects.
Coded in XAML files as %homefolder%, value is taken from the parameter value <homefolder> in the shortcut used to start the APL/Wapplication.
Other developers are finding value in setting an event callback function name within the XAML file; clearly there's an advantage here in keeping the entire GUI definition in one place. Intention is to bring my preprocessor into line with this (and also capture control names). Not quite sure why they seem to like starting the callback name with a ∆.
For examples of this approach, see the Code Structuring page.