I'm usng PM5 beta perhaps public 1 build 12738 (d32f517) on OSX 10.6.8 and I found the following error when saving an IPTC stationery:
I can select text in the filename box with shift and cursors also using Shift+Alt key (jump selection to start/end of next word) but Shift+Cmd (jump selection to start/end of the whole line) or Cmd+A (select all) does not work however they usually work in all the OS, browser and other program text input fields.