PaintSinglePar has been broken somewhere between release 23.1 and release 24.3a. The most obvious manifestation of this bug is that ListBox1 of TWPStyleDlg is no longer populated with text and remains blank.
This also affects my own style dialog which is not based on TWPStyleDlg, but calls PaintSinglePar directly.
I am sure you will fix this with your usual promptness.