Only Boolean Constants can be Used with If
From Xojo Documentation
Error message
Only Boolean constants can be used with #If...#Endif statements.
Sample Code
A 'regular' Boolean variable cannot be used as shown here.
See Also
DebugBuild, XojoVersion, XojoVersionString, TargetBigEndian, TargetCocoa, TargetDesktop, TargetLinux, TargetLittleEndian, TargetMachO, TargetMacOS, TargetWindows constants; #If statement.