Screenshot without window borders takes wrong image

[xyzdragon]

When trying to make a screenshot of a window without its borders the screenshot contains the content shifted up by the amount of vertical window borders plus it contains a black filled area at the bottom as large as the amount of the shift.

See attachment. The left image was taken with the "Window borders" option and is 152x173 pixels large, the right image was taken without the option checked and measures 150x150 pixels which is correct, but as can bee seen the circle isn't centered anymore, but shifted.

Magenta denotes unused space, as I had to merge both screenshots in order to upload as a single attachment.

I'm using kazam 1.4.5 'NCC-80102' on Debian sid with Linux 3.16.0-4-amd64 and XFCE 4.12 with the Sable Window Theme, but the bug seems independent of the window theme, I also tested the XFCE default theme.

The program I wanted to make a screenshot of is a Processing program defined as:

void setup()
{
    background(255);
    size(100,100);
}
void draw()
{
    ellipse( 50, 50, 50,50 );
}

Edit: Also the Area Screenshot option does not work with that window, only printing a gray image. I guess because it is an OpenGL-window (not sure that it is).

[xyzdragon (xyzdragon)]

Problem also appears when making borderless screenshot of xzoom. This might be easier to confirm and hints to a more general problem.