Align tab
     
    This tab is accessible only while in image mode. It is used to control the 
    alignment process :
      
        - The "x" an "y" numeric fields set the origin (in pixels unit) of the
	  align square (0,0 is at the bottom left corner).
 The square position can also be (and usually is) changed by dragging 
	  it in the image frame.
 By holding the option key while finishing the drag, the square 
	  position is set only for the highlighted entry in the list frame.
 For best results : on images of the moon, frame a conspiscuous 
	  detail ; on planets images, frame the entire planet.
- The "side" button menu sets the align square side, this side is a 
	  power of two, not larger than the lower side of all the images and 
	  movies in the list.
	
- The "Ref" checkbox sets the highlighted entry in the list frame to 
	  be the reference image ; that is the image against which all 
	  others will be aligned. The default reference image is the first 
	  image of the list.
	
- The "Align" button starts to align each image selected for 
	  processing (ie: with a checkmark).
 Once started, it is impossible to select another tab and the "Align" 
	  button becomes a "Stop" button (you guess what it does ;o).
When this tab is selected, the image frame displays the image of the 
      highlighted line in the list frame. The align square is drawn as a red 
      square on this image.
      The left and right arrow keys, delete, backspace, space and return keys 
      act as in the list tab.
    During alignment process, each processed image is :
      
	- highlighted in the list frame, 
        
- its name displayed green if alignment is successful, 
	
- its ∂x and ∂y columns updated, 
	
- displayed with its alignment offset corrected, in the image 
	  frame.
 This last feature can be disabled in user preferences, to speed up 
	  the alignment.
Analyze tab ...