Widgets embedded in QGraphicsView view have limited coordinates under X11

Widgets embedded in QGraphicsView view with a QGraphicsProxyWidget are limited to signed 16 bit int coordinates. This appears to be the results of X11 handling of the coordinates, even though the widgets are embedded in a graphics view, and not on the screen. This is because window coordinates under X11 are limited to signed 16 bit integers.

In my use case I am trying to display an editing widget above a graphics item. But when the item has a scene coordinate (x or y) greater than 2^15, the widget is instead displayed off of the viewport with a negative coordinate. The coordinates "wrap around" to the negative.

Example source attached showing problem. Notice that button2 is not at coordinate 100, 32800, but instead near coordinate 100, -32735.