Here's the link to it: http://trac.wxwidgets.org/ticket/15236
As Andrea Gavana instructed me, I have reported the documentation bug in wx.FileDropTarget.OnDrop() method of two missing parameter description texts.
If any wxWidgets dev is reading this, please feel free to fix this, so that wxPython Phoenix docs will be fixed automatically.
Update on the topic
The issue is that wxWidgets' docs don't contain parameter description of 'x' and 'y' for the OnDrop method of wxFileDropTarget. The wxWidgets' docs do, however, contain parameter description of 'x' and 'y' for the OnDropFile method, but not for the OnDrop method. So that is why wxPython Phoenix docs can't get descriptions for the OnDrop method. Can anyone fix this?