When calling FlashWindowEx, Window behaves abnormally in Windows 11.

The issue you're observing seems to be related to changes in how Windows 11 handles window states, especially when interacting with taskbar functionality and window management. The steps you're following, especially involving SW_SHOWMINNOACTIVE and FlashWindowEx, interact with window visibility and flashing behavior, which may behave differently in Windows 11 due to updates in the operating system’s taskbar and window handling behavior.

Let's break down the issue and potential causes:

Observed Behavior

1. Minimize state unintentionally restored: When you create a new window, minimize it with SW_SHOWMINNOACTIVE, and use FlashWindowEx, the window unexpectedly restores to the foreground when it shouldn't (based on your understanding from Windows 10 behavior).
2. Taskbar interaction and timing issue: This behavior only occurs when you close the window from the taskbar. Closing the window directly through the taskbar might not trigger the same sequence of events that closing it from an application window would. Windows 11 might have altered how taskbar window closing interacts with background window states.

Potential Causes

1. Changes in Windows 11 Taskbar Handling: Windows 11's new taskbar could manage window states differently, especially when calling FlashWindowEx. Windows might prioritize the taskbar's needs (i.e., showing the window as active when flashing) over keeping it minimized.
2. SW_SHOWMINNOACTIVE Behavior in Windows 11: It's possible that Windows 11 doesn't fully respect SW_SHOWMINNOACTIVE the same way as Windows 10. This command is supposed to show the window minimized without activating it, but the FlashWindow call might be interfering with this, forcing a restore or activation.
3. FlashWindowEx Interaction with Minimized Windows: FlashWindowEx is likely bringing the window into a "ready-to-interact" state, even though it's supposed to remain minimized and inactive. This might be a side effect of changes in the API’s behavior in Windows 11.

Potential Fixes/Workarounds

1. Use SW_SHOWNOACTIVATE Instead of SW_SHOWMINNOACTIVE : Try using SW_SHOWNOACTIVATE (0x04) instead of SW_SHOWMINNOACTIVE . This will show the window without minimizing it but also without activating it. This might prevent the system from restoring the minimized state: WindowApi.ShowWindow(form.Handle, (uint)WindowApi.SWCommands.SW_SHOWNOACTIVATE);
2. Delay FlashWindowEx Call : Introducing a small delay between the ShowWindow and FlashWindowEx calls might allow the system to correctly handle the window’s minimized state before flashing it. This can sometimes resolve timing-related issues with window management.
3. Explicitly Minimize After FlashWindowEx: After calling FlashWindowEx, explicitly minimize the window again to ensure it stays in the minimized state: WindowApi.ShowWindow(form.Handle, (uint)WindowApi.SWCommands.SW_MINIMIZE);
4. Modify FlashWindow Behavior: If flashing the window is necessary but you want to avoid restoring its state, try experimenting with the FLASHW_TIMERNOFG flag instead of FLASHW_ALL. This flag flashes the window without activating it or restoring it from its minimized state: FLASHWINFO fi = Create_FLASHWINFO(hwnd, WindowApi.FLASHW_TIMERNOFG, count, 0);
5. Check Windows 11 API Documentation/Changes: It's also a good idea to check Microsoft's Windows 11 API documentation or developer forums for any known changes to ShowWindow and FlashWindowEx behavior under Windows 11. Microsoft may have introduced or documented behavior changes.

Summary

The unexpected restoration of the minimized window is likely due to changes in Windows 11's handling of minimized and inactive windows, especially in conjunction with FlashWindowEx. You can try using alternative ShowWindow commands, introduce delays, or modify the flashing behavior to avoid the window being restored unexpectedly. Testing various configurations of window commands and flash options should help find a combination that works correctly under Windows 11.

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