In C# 4.0 I have an application that starts several threads. Each thread performs processing, opening and closing its own forms as necessary.
Each of these threads is intended to run independently (a dashboard using the Observer pattern summarizes the status of each thread). I want to be able to hide all the forms on a given thread and later make them all visible again, including any changes that might have taken place (forms opened or closed).
Right now what I'm doing is using Application.OpenForms. I can associate most of the open forms with a thread, so I can go thru the collection and display or hide the forms for a given thread. It's not perfect, but seems to be good enough.
The main problem seems to be that I can't preserve the z-order of the forms, so that when they are made visible, they're in the order of creation, not necessarily the z-order at the time of hiding. If I could record the current z-order state I'd probably be OK but I don't see how to do that.
On a technical note, I'm not really making the forms visible or invisible; I'm using TopMost and BringToFront() and SendToBack() to selectively move forms into or out of view with respect to a full screen form that acts as a visibility barrier (stuff on top is visible, stuff behind is not). I tried using Visible to hide or display forms, but recording the visibility state when hiding, and handling it when a form on a hidden thread was created turned out to be a bit tricky. Both approaches have the problem of distorting the z-order.
There are other problems with my OpenForms approach, but that's probably enough for now. I'm open to suggestions, either avoiding OpenForms entirely, or somehow dealing with the z-order problem.