You're screwed if the window position makes the title bar offscreen, and then you have to edit the .pd file, or edit pd.tk so that it never sets window positions (just delete the line that says "wm geometry").
just about any OS lets you resize a window which all borders are offscreen. windows just 'maximize' it from the taskbar. linux just mod1-right resize it..
there must be an extension to OSuX to make its WM not sux so much?