[lazarus] TFileListBox, TDirectoryListBox, TDriveComboBox

[P Jean dit Bailleul]

Under linux, how the properties Drive from TFileListBox and
TDirectoryListBox should react?
I suggest that it is only a dummy property that does nothing and return an
empty string.

I think also that TDriveComboBox should be available for compatibility only
even if under linux it is useless.

Is it ok?
P Jean dit Bailleul (jdb at abacom.com)