Via: uk.ac.york.vaxa; Wed, 22 Jul 1992 10:14:39 +0100
Newsgroups: comp.infosystems.gis
Date:         Wed, 22 Jul 1992 10:13:00 GMT
              <GIS-L@UBVM.BITNET>
From:         Peter Halls <PJH1@VAXA.YORK.AC.UK>
Subject:      Re ARCEDIT, or anything, under X Windows
X-To:         GIS-L <GIS-L@UBVM.CC.BUFFALO.EDU>

Sue@byron.u.washington,edu queeried the behaviour of arcedit under Openlook,
and Todd Fitzgibbon, from the US Geological Survey, pinpointed the root
accurately.  This is common to any applications under X - and windows based
on X, such as Openlook, Motif, DECwindows etc.

Whilst not claiming X expertise, I have written a couple of X proggies to try
to enable myself to uderstand better what is going on.  Perhaps the following
reflections may be of help.

ARCEDIT has, effectively, 2 windows - the graphic display and the text area.
One is used to display the features and to permit selection by means of the
point-and-click approach, the other to receive textural commands / data.  In
theory, were the device like, say, a Tek 4014 or 4207 (may they rest in peace),
it would be a simple matter for ARCEDIT (or any program) to 'select' keyboard
input and so not have to worry about 'focus'.  X, however, is NOT like that.
The 4xxx device could ONLY be controlled by one application at a time.  This is
not so for your X screen - only for each window upon the screen.  Typically,
you may have a mail window, an ARC window set - maybe more, open on your X
screen at any one time.  At present I have 4 active windows and 3 icons on my
X display.  Herein lies the problem.  If I type on my keyboard, how is X to
know which window I want to be associated with my keyboard at this moment in
time?  It may be that ARC is clamouring for input from the keyboard but that I
have first to respond to an urgent mail message from my manager - in such case
it cannot be left to the APPLICATION to 'grab' the keyboard (or mouse!) - it
**MUST** BE BEFT TO ME, THE USER, TO INSTRUCT X AS TO WHICH WINDOW I AM
ADDRESSING.  Nothing else can be acceptable.

Yes, it is annoying to have to 'select focus' every time - and, although I have
been using an X display for the best part of 2 years now, I still find myself
typing to the wrong window from time to time.  I do find MOTIF, where you only
have to position the cursor on the appropriate window, more convenient than
DECwindows where a positive 'click' on the window is required, but ...

Todd commented "This problem isn't fatal, but it would be nice to correct it."
Humbly, I think you are wrong, Todd.  I, for one, do not wish it to be
'corrected' because it would break all the advantages of X.

Maybe what Sue and Todd, and doubtless others, require is a Tek 4xxx style
emulator to run under X and which GIS, such as ARC, could be configured to use
INSTEAD of the X display?  This could then receive from the keyboard in
the current 'focus' and display the text in a sub-window that represented the
Tek 'text' screen, automaticcally flipping back to the graphic window and
'focus'.  Such would be taking you BACK to the old days, and old ways, but
if you really do not *want* the nice flexibility of working with X ...


Peter Halls
University of York

PJH1@UK.AC.YORK ... or t'other way about
Newsgroups: comp.infosystems.gis