Possible meant: "Window's resize widget is outside the viewport, so have to first move the window by dragging the titlebar until the resize widget is accessible, then resize, then drag the titlebar again to approximately restore the window position".
Still, this seems to be more logical to me than moving the window borders, since moving something in a suitable place first, in order to maybe manipulate it there, is much more like we would proceed with real-life objects.
(However, the window being rendered for an initial view in a way where not all the crucial controls are accessible is the real problem and arguable shouldn't happen at all. At this point, every action to fix this will probably be flawed. E.g., if we resize the window by dragging any of its visible borders, any action and/or cancel buttons will be still tied to the bottom part of the window, which is still off-screen, meaning, we're still stuck. On the other hand, dragging the window by its title bar, while maybe a more promising approach, may be impossible, as there is probably not sufficient screen estate left for this, to begin with.)
