C++Builder supports compiling design-time packages that contain Delphi source files. However, if any of those Delphi sources make reference to IDE-supplied design-time units such as DesignIntf, DesignEditors, and ToolsAPI that exist in DesignIDE100.bpl, you must take steps to ensure that the references can be resolved by the C++Builder package.

1. The Delphi compiler must be able to resolve units in the DesignIDE package. To enable this, in the C++Builder package project, go to ProjectOptionsDelphi CompilerOther Options.
2. Add —LUDesignIDE to the Additional Options field.
3. The C++ linker must be able to resolve the reference inside the compiled design-time .obj to link. To allow this, in the C++Builder package project, select the ProjectAdd To ProjectRequires tab.
4. In the Package name field, enter designide.bpi and click OK.