Gets a resource value from the resource database (for example, ``WIN.INI'', or ``.Xdefaults''). If file is null, the platform-specific resources file is read.
The resource value is keyed on the combination of section and entry. The "mred" section is reserved for PLT.
The return value is #t is a value is found, #f if it is not. The type of the value initially in the value box determines the way that the resource is interpreted, and value is filled with a new value of the same type if one is found.
See also wx:write-resource.