bizarre DG problem

[Phil Davis]

Hi folks,

My client just called me to report one of his customers' data grids in a 
very weird state. I've never seen this before and thought I should ask 
if anyone else has, and how to prevent it if possible.


System:
macOS 10.13.x - High Sierra
LC 8.1.9 Community


Background:
This DG is automatically redefined regularly to display different sets 
of columns for Orders data, Clients data, Purchases data, etc., and is 
then loaded with data of that type. The redefinition/reloading happens 
when the customer clicks a button for that type of data. This has worked 
flawlessly for many years and I don't suspect it as the source of the 
problem.

The DG is in a window that is not resizable. so it's rect is constant.


DG properties:
vScrollbar = true
hScrollbar = auto


Symptom:
Inside the customer's DG, grp "dgList" is horizontally out of alignment 
with the hScroll of the DG. When the hScroll is 0, the left of grp 
"dgList" should be the left of the DG, but instead it's left is near the 
center of the DG. This prevents the display of all whole or partial 
columns that are to the left of the group's left edge.


Fix:
(realign the 'dgList' group with the hScroll of the DG)
set the hScroll of the DG to 0
set the left of grp "dgList" of DG to the left of the DG
refresh the DG


Cause:
?????
I'm trying to understand what caused it so I can prevent it in the future.

Any ideas are welcome.

Thanks -
Phil Davis

-- 
Phil Davis