I had a similar case with a different app where the title bar was exactly between my two monitors, unfortunately all other tips here did not work and others seemed to complicated to make sense.
I thought the drag-resize solution sounded best, but although my window is resizable from all sides and corners. dragging anywhere else but the titlebar did not work and also holding down longer does not change anything.
But the only key that makes a difference is pressing the alt/options key while resizing the window from the bottom side, because the this resizes not only the side that you drag on, it actually also resizes the opposite side, which brings the toolbar back in screen.
alt + resize-drag