User`s guide

; of an error number. The code line is:
TYPE $ERROR(IOSTAT(lun))
Managing Windows
Windows can be:
l Hidden (but not deleted)
A hidden window is removed from the screen but not from graphics memory, and it
can be retrieved at any time:
FSET(glun) "/NODISPLAY" ;Hide a window
FSET(glun) "/DISPLAY" ;Redisplay a window
l Sent behind the parent's window stack:
FSET(glun) "/STACK -1"
l Brought to the front of the window stack:
FSET(glun) "STACK 1"
If you will not be reading events from a window, open it in write-only mode to save memory
and processing time.
Only the task that opened a window in read/write mode can read from it (monitor events).
Multiple tasks can write to an open window. A second task can write to an already open
window by executing its own ATTACHand OPEN for the window. The logical units' numbers
need not match, but the window name must be the same. If a task has the window Test
open, other tasks can write to the window by:
ATTACH(lun_1, 4) "GRAPHICS"
FOPEN(lun_1) "Test /MAXSIZE 200 200 /WRITEONLY"
Graphics Programming Considerations
V+Language User's Guide, v17.0
Page 258