Deep Parsing

If the "Deep Parse" switch in the project options is off only units explicitly referenced in a project will be loaded and parsed.

program ThrdDemo;

uses
  Forms,
  ThSort in 'ThSort.pas' {ThreadSortForm},
  SortThds in 'SortThds.pas';

{$R *.RES}

begin
  Application.CreateForm(TMyThreadSortForm, ThreadSortForm);
  Application.Run;
end.

In the ThrdDemo project only units "ThSort" and "SortThds" are loaded, "Form" is ignored because its file name is not specified.

When this is parsed the unit drop down list will show.

If the "Deep Parse" switch is set then units found in "Use" clauses not explicitly referenced by the project are searched for using the search path defined in the "Project Options". If the unit is not found and the "Include VCL Source" switch is set then the directory tree starting with "VCL Path" is searched for the unit.

Here the "Deep Parse" switch has been set but not the "Include VCL Source" switch. The unit drop down list shows the units it could not find with an error indicator.

If the "Include VCL Source" switch is set then the units drop down list will show,