Why “Setup Status windows” is going to background?

[Fox_Bruce]

During installation, the installer UI goes out of focus and goes behind any windows that were already opened.

Step to reproduce:
Open file explorer windows
Run setup.exe
Observe that at the start the installation, the UI is in focus, in front of all windows (Prepare Setup windows)
Then it disappears to the background. (Setup Status windows)

[rguggisberg]

Is it possible that you inherited this setup and someone intentionally made it work that way?
You might search through your custom actions. If you have any InstallScript code do a search for something like

nHwnd = FindWindow ("", YOUR_PRODUCTNAME);
SendMessage (nHwnd, WM_SYSCOMMAND, SC_MINIMIZE, 0);

Which would minimize the screen.
If not... log the install and look in the log.

[Fox_Bruce]

I am finding the problem and solution.
Add command before SetStatuswindows. Command: Enable (STATUSEX);

The normal installer, “setup status windows” is for transfer file to target folder.
My installer is tried to change the rule for control progress bar.
So, that is different with normal installer.