Note: Custom changes to the vcl are not supported by Borland or Borland Developer Support. -But if you choose to do so... VCL source code changes should never be made to the interface section of a unit. VCL source code changes should only be made to the implimentation section. The safest way to make changes to the VCL is to create a new directory called "patched". Copy the VCL file you want to change to the new directory. Make your changes (with comments) to the copied file. Next, add the path to your patched directory to the beginning of your library path. Restart Delphi/C++ Builder, and rebuild your project. The library path setting can be found off the main menu of: Delphi : Options | Environment | Library Delphi 2 : Tools | Options | Library Delphi 3 : Tools | Environment Options | Library C++ Builder : Options | Environment | Library