To get a FilePicker: 
   xMultiServiceFactory->createInstance of "com.sun.star.ui.dialogs.FilePicker"
   (aka. FILE_OPEN_SERVICE_NAME)

e.g. in OpenDocExec_Impl:
-> if( !pFileNameItem ) sfx2::FileOpenDialog_Impl
-> FileDialogHelper aDialog(...); aDialog.Execute(...);
-> mpImp = new FileDialogHelper_Impl(); mpImp->execute();
-> FileDialogHelper_Impl::implDoExecute
-> aService = FILE_OPEN_SERVICE_NAME; mxFileDlg = mxFileDlg.query( xFactory->createInstance( aService ); mxFileDlg->execute()

dialogs.FilePicker implemented by:
   SvtFilePicker (svtools/source/filepicker/filepicker), the cross-platform version
   also implements the service com.sun.star.ui.dialogs.OfficeFilePicker

   CFilePicker (fpicker/source/win32/filepicker/FilePicker.cxx, delivered;
   old copy in sysui/source/win32/filepicker/FilePicker.cxx, not delivered),
   the win32 native file picker
   also implements the service com.sun.star.ui.dialogs.SystemFilePicker

SvtFilePicker::impl_createInstance (factory for SvtFilePicker) creates a
SystemFilePicker if available (registered) and not disabled by the user
(SvtMiscOptions.UseSystemFileDialog(), an unbreak-me option?)

SvtFilePicker implements (svtools/source/filepicker/filepicker.hxx) the interfaces
   XInterface x
   XTypeProvider x
   XServiceInfo x
   XExecutableDialog (parent-iface of XFilePicker) x
   XFilePicker (parent of XFilePickerControlAccess) x
   XFilePickerControlAccess x
   XFilePickerNotifier x
   XFilePreview    x   
   XInitialization x
   XFilterManager x
   XFilterGroupManager x
and via OCommonPicker (commonpicker.hxx)
   XControlAccess
   XControlInformation
   XEventListener x
   XCancellable x
   XInitialization x
   
For a description of the interfaces:
http://api.openoffice.org/docs/common/ref/com/sun/star/ui/dialogs/FilePicker.html

CFilePicker implements the interfaces with x

XFilePreview: dialog can only preview bitmaps

XControlAccess: for setting properties of controls inside the dialog
XControlInformation: get list of control, their properties


Dig in:

svtools/source/filepicker/filepicker.cxx (HasSystemFilePicker)
SvtMiscOptions::UseSystemFileDialog
    Office.Common/Misc ('UseSystemFileDialog')


** Fixing FilePickerWorkaround:

    fpicker/source/office/OfficeFilePicker.cxx: needs re-work

    LXR: has a lot of hits - at least 1/2 sampled just use [0]
	 unconditionally.

    sfx2/source/dialog/filedlghelper.cxx: 
	+ GetMPath [!]
	+ 'execute'

