Can't select whole screen, off by one pixel on both axes

[tabitha-vi]

If I select from any corner to the opposite corner, it always selects one pixel short on both axes. My screen is 1600x900, but the output of slurp is limited to 0,0 1599x899

The version I have installed is 1.2.0, and I'm using it with sway 1.5.1-r1

[tabitha-vi]

Also, when running slurp -b 00000000 -c 00000000 -s 000000ff, it's visible that there's a 1-pixel gap on the top and left sides of the screen, and a 2-pixel gap on the bottom and right. The extra 1-pixel around the whole screen may be a separate issue, but it illustrates what's happening I think.