The dialog is the "dialog_edit_component_in_schematic.cpp" file.
Because the tooltip for this button clearly states its intent as:
"Set position and style of fields and component orientation to default lib value.
Field texts are not modified."
It is working as designed, and therefore not a bug. At best it should be categorized as as feature request. We could add a question dialog to ask if field values should also be reverted to what is in the library.
Another, perhaps more important observation is that this button only operates on two of the fields, REFERENCE and VALUE. I would think this is a larger problem. Maybe we need to get rid of the global button in the dialog, and provide one that operates per field, but I don't know how useful this is in general. The user can simply drop in another symbol from the library, no?
Any other comments about how this button should operate, or if it is needed at all?
confirmed in 2010-05-05 BZR 2356 Stable on windows7