Form not visible but seems to be open somewhere!

[krag]

I have been developing a project with 4 different interlinked database files (Windows 10 / Office Pro Plus 2013 / Laptop Japanese version):
1. Company and contact data
2. Machines installed data
3. Creating proposals for machine sales to clients
4. Costing data for machines in stock and proposals made to clients
The whole system has been running well without any major issues for last 2 years.

Suddenly for reasons unknown, a month back, in some of the database files, the starting master panel form is not visible but seems to be open somewhere in the background.
Or, some of the secondary forms which should pop-up by a button click on master panel, are invisible but can see that they are open from the task bar at the bottom.
To actually open the form visibly, I have to first open it in design view mode from navigation panel, which seems to be okay.
From design mode, if I open the form view mode, then it works fine.

I did not change any of the form properties at all.
Possible reasons that I guess so far are:
1. Some Windows / office update has affected the operation.


2. Use of extended secondary display from my laptop.

Actual user of the system in India using English version on both Desktop and laptop has no problems whatsoever.
Now, recently the user upgraded to 2016 office version from 2013 (English).
So I also upgraded to 2016 (Japanese) version yesterday hoping that above invisible form problem will disappear.
To my dismay, the problem remains as it is in 2016 version also.

I am now starting to work on the upgrade version of the application and need to resolve this issue before proceeding further.
Any advice will be highly appreciated.

[June7]

Just reading the thread title made me think of secondary display. Have you tested without the second display?

[krag]

Tks June7 for the comment.
I did consider that and tried without secondary display but problem was there.
One way that I could overcome this issue was as below:
Change the popup property of the problem form to "no" (my original setting is "yes").
Then when I open the form directly from starting or from other form button, it works fine.
If I now reset the popup property back to "yes", it seems to work without problem.
When I use the secondary display again once and go back to without secondary display again, the problem seems to recur.
I have to check in detail when I am back in my office from my travelling, to use the secondary display to re-confirm.
Menawhile if you have further suggestions, please do let me know.

[krag]

Today I tried re-testing with and without extended display.
The problem is as I explained in my previous message.
I think following factors or their combination is affecting the forms:
1. Use of extended display
2. Popup property of the form
3. Size of the form - I designed the form size to fit into a larger display panel for desktop.
So on my laptop, it tends to overflow outside the display screen.
Here if extended display is used, it seems to automatically display in the other display.
I am not very sure about this.
Is there any way to automatically check if extended display is in use and control the behaviour of the form opening?

This is not a very major problem right now as I can ask the user not to use extended display at all for this application.
However, if there is a solution available, it would be great.
Incidentally the forms are opened in single form view.

[June7]

Don't think I've ever set Popup property to yes. Never had a need for users to be able to move form. I will set Modal to yes but only when I am ready to deploy. Popup and Modal are a nuisance during debugging.