Comment 3 for bug 577610

my tests gave:
- capture(x,y,w,h) always works with any w and h if both x and y are 0

the buggy capture is only with x and/or y > 0.

if both x and y are greater than w and h the captured image is totally black.

if x and/or y are < w/h respectively, you will have the upper left part of the image in the lower right part of the captured image.

if you add the x and y value to w and h respectively, you will get a capture with
- width = x+w and height = y+h
- the wanted image in the lower right corner with the relative position x,y
- and the rest being black.

example:
capture wanted: capture(200, 100, 200, 100)
you say capture(200, 100, 400, 200)

If you now could say capture on the captured image, capture(200, 100, 200, 100) would give you the wanted image.