Question

I am using WinForms for a C# project and my main form has a simple button that uses ShowDialog(this) on a second form to show it.
Like this:

if (myParameterForm.ShowDialog(this) == DialogResult.OK)
   {//stuff happens}

As per my requirements, when the child form is visible, you cannot access the parent form.

For the past year this child form has been the bane of my application as it mysteriously manages to hide behind its parent form from time to time. The reason this is such a big problem is because the software is designed to be used from a touchscreen kiosk, so the user only has access to a touch-screen, but the child form has locked input from any form but itself till it is acknowledged (closed with ok or cancel).

On load the child form uses “this.TopMost = true” just in case, I added this as an effort to fix my problem.
I use no other visualizing functions on the child form, the thread calling the form literally waits there till the form is closed.

Since the user has no access to a keyboard, or anything but a touchscreen I’m miffed as to how the child form manages to hide behind the parent form. I actually have been unable to replicate the behavior, and have only seen it as a result of responding to service requests.

I want to avoid using a timer to continually check if the form is TopMost because it just seems wrong. Should I reconsider? What event could possibly be occurring that is banishing my child form backstage?

I’ve tried using the search, but as far as I can tell I’m doing this correctly… Assuming that there is some sinister 3rd party application causing occasional hijinks, what is the best way to detect and rectify this situation automatically without throwing in a periodic check? I am not sure that the VisibleChanged event is what I’m looking for.

Answer 1

I can reproduce the behavior you are describing by minimizing the child window when it is displayed using ShowDialog. Is it possible that something is minimizing the child window? You could try disabling the control box for the child window to see if that helps. I would probably also set ShowInTaskbar to false for the child window (for usability reasons).