Imports and Subfolders and Links (Oh, My!)

[Ron Tarrant]

Trying to wrap my brain around imports, etc.

In various places around the Internet, I've read that if I have 
modules in a subfolder/subdirectory, my import statement would 
look like this:

import subfolder.ModuleName;

And in the module files, the first statement is:

module ModuleName;

However, I'm having trouble getting past the compile errors.

Scenario:
current folder contains - main.d

In main.d, the import statements:
import app.CountryTreeView
import app.CountryListStore

In the subfolder (named: app) I have two module files:
  - CountryTreeView.d (module CountryTreeView)
  - CountryListStore.d (module CountryListStore)

When I compile using:

dmd -m64 -Lgtkd.lib main.d

I get a bunch of unresolved external symbol errors for classes 
and modules. The import statements in main.d don't import 
anything from the subfolder.

Removing 'app.' from the import statements and compiling with:

dmd -m64 -Lgktd.lib main.d -Iapp CountryListStore CountryTreeView

it works.

Two questions:
1) Under what circumstances would I prefix the folder/directory 
name in a statement importing modules I've built myself?
2) What would the dmd compile command look like?