feature request: ability to always filter for all ratings

tl;dr: it would be great to have the option to select any rating filter, independent of (yet) existing files at that rating. 
 
probably like many pro photographers, my main use for fastrawviewer is culling the raw files before importing into lightroom. in doing so i run through the set several times, populating and changing ratings. in the process i use different filter ratings to compare the respective sets in each rating. something very annoying in that process is that it's not possible to easily apply a filter for e.g. *** and up, simply because a **** filter can't be applied when no **** files are (yet) present. so my usual procedure is to rate an arbitrary file higher, select the higher rating filter, and rate down the same file again. all that only to be able to select all higher filters (in this case **** and *****).