I've had nothing but problems with the windows preview handler. For the child dialogue boxes (open/save etc.).
I got k lite codec pack, vlc media player, pdf xpress etc. All those things that add preview handlers. But I still can't play videos, look at .rtf .dmp files (multiple issues). I almost have to shell out good money to buy "File Viewer Plus" just to look at certain file types. What a stupid waste of money.
The dopus handlers work perfect in the dopus preview pane. Why not let us choose these handlers to override windows too? Not just for dopus exclusively.