It's just me or the "file exists" dialog shows up with just two icons and no textual info (but the file names perhaps) about the file sizes for everybody? I have to resize it for every item in order to know whether it's dealing with duplicates or different files, if the icon preview is the same.

I know that some rc files set the default/last window size. Is there something similar to that for individual dialogs?

I'm wondering if that may be a matter of using a certain theme/style (or configuration thereof) or openbox as well, rather than something that occurs in regular KDE (albeit I've read in the blog of a KDE developer that this sort of thing is somewhat recurrent).

I'm not sure if dialog sizes are saved along with the main window state. If your tries with different styles yield no results, it may be worth opening a bug.