There's a note in the release notes:
Linux - clanGUI file dialog code exists on ClanLib 2.4 (Development). If they require backporting, please let us know. It would require clanGUI to use gtk as a dependency.
Well, I need this backported, so I'm letting you know! I'm doing a level editor in clanlib for Stone Ring and I need the dialogs to open and save levels.
Depending on GTK is fine.
Let me know if I can help.