When a pixel graphic (raster image) format is selected as the
current export format and a pixel image is selected, the current
resolution of the image will be adopted. If the
Whole page icon
is active or a different type of frame is selected, a click on this
icon sets the current zoom magnification as the output resolution. In
other words the graphic will be exported exactly as you see it on the
screen at the time.
With vector graphics this icon does nothing.