There are situations when it is more suitable to set source position by typing in pixel coordinates than dragging source on the screen.
One reason is that is is sometimes not easy to select source by clicking on it as it is covered with other, larger source. When source is selected on the list it cannot be moved (at least I was unable to find haw to do it - moving by keyboard cursors does not work and clicking on it to drag deselects it and selects other source that is above).
Other reason is that sometimes it is needed to align several sources positions and dragging is not the best way to do it. It is easier to just type in coordinates.
One reason is that is is sometimes not easy to select source by clicking on it as it is covered with other, larger source. When source is selected on the list it cannot be moved (at least I was unable to find haw to do it - moving by keyboard cursors does not work and clicking on it to drag deselects it and selects other source that is above).
Other reason is that sometimes it is needed to align several sources positions and dragging is not the best way to do it. It is easier to just type in coordinates.