I just updated the source and apparently something has changed because now  opening any  native Gretl  data file returns an error like the following:
---
Data file is empty

Error executing script: halting
> open mroz
 ---

The same for djclose, sw_ch14..and any other file. Anyway if I try to access them by the menu Gretl opens them without problems. Even stranger, if i give the complete path with a command like

open /usr/local/share/gretl/data/misc/mroz.gdt [ and the file does exist]

it returns the same error

Cheers