Gtk Radiant 1.5 - mesh, curves

[FearzEnemy]

All meshes and curves are invisible, even on older maps

[Eraser]

They're probably filtered out. In the "view" menu there's a sub menu (either "show" or "filter", can't remember which one right now) that allows you to toggle visibility of specific things.

[Theftbot]

Try pressing Ctrl-P