Many of the supplied plugins provide PDF output. PDDF output is generated using a PHP library called TCPDF. ImpressCMS (as of version 1.2.2) includes an older version of TCPDF. Gwloto will function with this version, but there will noticeable issues with some plugins. For best results, we recommend installation of the current version of TCPDF
Gwloto will look for TCPDF in the modules/gwloto/tcpdf/ directory. You can also direct gwloto to load TCPDF from any location with a module preference setting.