[Lazarus] How to switch a project from 32 to 64 bit (on Windows 7 x64)?

[Bo Berglund]

I started out on a project using Lazarus/Fpc 32 bit (2.0.0/3.0.4) and
now I want to switch to the 64 bit version of Lazarus/Fpc.
I have installed both 32 and 64 bit versions using the downloadable
installers so they are separate programs in their separate folder
trees.

I thought that I could start Lazarus 64 bit and then open the 32 bit
project and save it as a 64 bit project afterwards, but that failed
completely...
Turns out I have to also install some dependencies that the project
uses. Most important is the PasLibVlc library...

Since Lazarus can compile across platforms, can it also be directed to
compile on the *same* platform (Windows) but using different bit
versions (32 bit and 64 bit)?

Since I have both installed on my laptop it would be nice to be able
to manage both 32 and 64 bit versions from the same environment, if
possible.

But how should I go about telling my Lazarus 32 bit about the 64 bit
compiler already installed (it is the same version)?

And how do I differentiate between the different target executables
when building? Can Lazarus be told to build both at the same time?


-- 
Bo Berglund
Developer in Sweden