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            Redisplaying Text Fields in a Dialog Box

                       September 25, 1986

You  may  have noticed that Redo_Dialog does  not  redisplay  text 
fields  that you have changed using Set_Dtext.   This  is  normal, 
since Redo_Dialog does not actually redraw the dialog box.

The solution is to use the undocumented but ever-popular Obj_Draw.  
How do you use it?  Let's see now...

First you need to declare Obj_Draw so your program can access it.

Include  the  folowing  lines in your program  (after  global  VAR 
declarations):

{ Now we declare the obj_draw as external... }

PROCEDURE Obj_Draw( BOX : Dialog_Ptr;
                    ITEM : Tree_Index;
                    DEPTH, X, Y, W, H : Integer ); EXTERNAL;

{ The rest of your program follows... }

What  are  all those parameters?   Here is a  brief  (too  brief?) 
description of each:

     BOX           the dialog box pointer

     ITEM          the  item  you  wish to redraw  (the  one  you 
                   changed with Set_DText)

     DEPTH         how  many  levels  deep  the  tree  should  be 
                   redrawn.  0 through 8 are safe numbers, but we 
                   recommend 1.

     X, Y          The coordinates (in pixels) of the upper  left 
                   corner of the clipping rectangle.   Set  these 
                   equal to the values returned by Work_Rect  for 
                   window handle 0 (the entire desktop).
 
     W, H          The  Width  and  Height  (in  pixels)  of  the 
                   clipping  rectangle.   Set these equal to  the 
                   values returned by Work_Rect for window handle 
                   0 (the entire desktop).

Now,  after  you have changed your text fields in your dialog  box 
using  Set_DText,  all  you have to do is call Obj_Draw  with  the 
proper parameters and the text will be redisplayed.

Obj_Draw may be used to display a dialog box without ever  waiting 
for interaction.   A good example of this usage is the format  box 
when formatting floppy disks in the GEM desktop.


      }
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