rectangle frustration (or any shape)

[bbxrider]

been trying for hours just make a simple rectangle to carve out an area
for visual reference to the whole project or it might remain for a reference
when the project eventually gets exported for printing 

please see attached

I would think the rectangle isssues would apply to any shape so that helps to 
tone down the big frustration here trying to do something which I would have
thought to be really simple considering all the sophisticated image manipulations
available in gimp