After importing a Xilinx project I added a new vhdl package file using the wizard. The package file was not automatically added to the library. The outline view also didn’t show the package contents. Doing the same for a non Xilinx project will add the package to the library.

In the Xilinx project all source files are added to the library separately, in the non Xilinx project library work is added on a directory level. I had to add the vhdl source to the library by hand. A menu option to add the file to the library would be nice.