Defines the interfaces and classes used by the property editors in the IDE.

To use the  DesignEditors and DesignIntf units with Delphi, you need to add the following compiler option on the Compiling page in Project Options:

-LUDesignIDE

With C++, you need to ensure that $(BDS)\include\windows\vcl\design is added to the INCLUDE path, and that designide.bpi is added to the Requires of your package.

For more information, see the comments in the source; the DesignEditors.pas source file is liberally commented.