Writes a resource value into the resource database (for example, ``WIN.INI'', or ``.Xdefaults''). If file is null, the platform-specific default resource file is used.
The resource value is keyed on the combination of section and entry. The "mred" section is reserved for PLT.
Note that it is considered bad manners to write to the ``.Xdefaults'' file under X Windows, although the ``WIN.INI'' file is fair game under Windows.
The return value is #t if the write suceeds, #f otherwise. (A failure indicates that the resource file cannot be written.)
See also wx:get-resource.