I'm trying to simulate the rare situation where a user starts my game, but then gets impatient and/or clicks on something before the window appears. To debug this problem, I placed a Sleep(1000) right before my game window is created to provide a delay. Then I start my game, and click on another (folder) window to bring it to the foreground before the game window opens.
What happens is that my app gets the typical WM_ACTIVATEAPP + WM_SETFOCUS messages of a newly created window, and that's it. It never receives a WM_KILLFOCUS, or any other message that differs from starting the game with normal focus. To check this, I logged every message type the window received in the foreground and background, then compared them.
To be clear about this behavior, once my game receives WM_SETFOCUS and is behind another window, I can click on buttons and type into text boxes in that front window without my game window ever getting a WM_KILLFOCUS message.
I'm currently fixing this problem by comparing my window handle to GetForegroundWindow() after I create the window - and if it doesn't match, I call SetFocus(null) to remove input focus and trigger WM_KILLFOCUS. This seems to get around the issue by allowing Windows and my program to *notice* it is unfocused. But it feels like a hack. I'm hoping there is a better solution. edit: This temporary fix causes another problem: the next time my game is actually focused (such as by clicking on it in the task bar or using alt+tab to switch to it), Windows never sends it a WM_SETFOCUS message, even though the window is brought to the foreground. However, the next time I click or alt+tab to it, it does send the message. So it's as if the first focus is ignored because I called SetFocus(null).
Could any of these issues be related to my window's creation styles/options/flags? The style flags I use are (WS_POPUP | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_VISIBLE). Are there any other things I may be doing wrong to cause this to happen? Or is this just a limitation/bug/design of Windows?
edit: it looks like this poster had the same problem: http://www.gamedev.net/topic/618042-win23-api-detecting-lost-focus/
Thanks for any advice
Edited by Stephany, Yesterday, 08:04 PM.