title: What prevents adding the 64-bit Windows platform to VCL component packages?
body: <p>With most Delphi and C++ Builder projects, including component packages, you can add a 64-bit Windows target by right-clicking on the Target Platforms item in the Project Manager and selecting Add Platform, then choosing '64-bit Windows' in the resulting dialog.</p>
  
  <p>Recently while installing components in a new installation of RAD Studio XE4, I've been unable to do this for some components.  For example:</p>
  
  <p><img src="https://i.stack.imgur.com/ZveL0.png" alt="The Add Platform dialog with only OSX and 32-bit Windows showing"></p>
  
  <p>This specific example is <a href="http://www.tmssoftware.com/site/advpolylist.asp" rel="nofollow noreferrer">TMS's Advanced Poly List</a>, but it's happened for other component packages as well - but not all.  Some have the target available, and for those I can build the package and create a 64-bit VCL forms application that uses the component fine.</p>
  
  <p><strong>What is preventing the Win64 target appearing in the dialog, and how can I re-enable it?</strong></p>