Don't know if this is a bug or intended.
In the treeview panel the "Del" key doesn't trigger "Delete" for a folder. The right mouse click menu also doesn't mention the shortcut.
In the thumbview panel the "Del" key does trigger "Delete" for a folder. In this case the right mouse click menu does mention the shortcut "Delete Del".
Even if it is not a bug, for consistency I believe it would help to have the "Del" key behave the same.
The same seems to apply to Ctrl+C, Ctrl+X and Ctrl+V.
F2 (for rename) works in both panels
XnViewMP v0.64 64bit on Win8.1