XRandr GUI that supports Transform?

I'm trying to correct for keystone distortion using a small Ubuntu/Debian box and a projector. The intended effect is for the desktop to be distorted in a fashion similar to this:

This can be accomplished using the --transform option of xrandr; however, in order to achieve exact results in a reasonable amount of time, I need some sort of GUI to drag the edges of the screen into place.

I can't find an XRandr GUI that supports transformation. Could anyone help with this?

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