Why DVD subtitles are zoomed with the picture?

I’ve got WD TV Live two days ago. I like zoom feature because I prefer to watch fullscreen picture without black bars. Player doesn’t offer 1.32x or even 1.3x to fill the whole screen by 2.35:1 anamorphic movie.

I noticed an issue with zoom and subtitles. When I play DVD movie (from VOBs) and using zoom (1.1x or 1.2x), DVD subtitles are zoomed with picture. Subtitles are cropped (partially displayed out of the scrren).

This is strange, because zooming the bluray movie (m2ts) retain subtitles intact.

I think this is because DVD subtitles are rendered before zoom. Could it be fixed?