I'm trying to find a way that during an Maintenance Mode mode, the user has the option of selecting, New Installation, and installing our application into a new directory (while leaving the current installation alone). I know this is going to cause problems on uninstall, but I'm willing to live with that (since this is an uncommon operation anyway).
I've been able to set up the UI (in OnMaintUIBefore) so they have the option (as well as repair and uninstall) and select a new path (which is assigned back to INSTALLDIR). However I can't get it to actually install into that directory.
If I call FeatureReinstall it creates the new directory but it's blank, and it looks like it reinstalls into the previous installation directory. Looking at the MSI log, CostFinalize sets INSTALLDIR back to the original installation directory instead of the user selected one.
A pure InstallScript project (using multi-instance support possibly) might be better suited to this situation. Basic MSI and InstallScript MSI projects use the Windows Installer to perform the installation. The Windows Installer does not allow the target installation path to be changed once a product is installed (see http://msdn2.microsoft.com/en-us/library/aa367852.aspx). As such, it would be necessary to uninstall the product first and then install it again to a different location with an MSI based project.
