C# Discussion Boards - CodeProject

17-Jul-09 0:38

Hi all.

I've spent 3 days searching for this and trying different alternatives, but nothing works.

I have an app which works perfectly on Windows XP:

1) Monitorizes some windows.
2) When one of them reaches a certain state, my app brings it to the foreground.
3) Then, does something with it (moves the mouse, clicks something...).
4) Finally, my app brings to the foreground the window that was visible before step 2, so the user can resume his work where he was before.

My problem is that, when I execute this app on Windows Vista, the step 4) seems not to work. I've been reading a lot these days, and I've found that the "SetForegroundWindow()" method I was using works differently on Vista, so I started using "AttachThreadInput()" following an example that I found somewhere:

private void activateWindow(IntPtr hWnd)
{
    if (IsIconic(hWnd))
        ShowWindowAsync(hWnd, SW_RESTORE);

    ShowWindowAsync(hWnd, SW_SHOW);

    SetForegroundWindow(hWnd);

    IntPtr foregroundWindow = GetForegroundWindow();
    IntPtr Dummy = IntPtr.Zero;

    uint foregroundThreadId = GetWindowThreadProcessId(foregroundWindow, Dummy);
    uint thisThreadId = GetWindowThreadProcessId(hWnd, Dummy);

    if (AttachThreadInput(thisThreadId, foregroundThreadId, true))
    {
        BringWindowToTop(hWnd);
        SetForegroundWindow(hWnd);
        AttachThreadInput(thisThreadId, foregroundThreadId, false);
    }

    if (GetForegroundWindow() != hWnd)
    {
        IntPtr Timeout = IntPtr.Zero;
        SystemParametersInfo(SPI_GETFOREGROUNDLOCKTIMEOUT, 0, Timeout, 0);
        SystemParametersInfo(SPI_SETFOREGROUNDLOCKTIMEOUT, 0, Dummy, SPIF_SENDCHANGE);
        BringWindowToTop(hWnd);
        SetForegroundWindow(hWnd);
        SystemParametersInfo(SPI_SETFOREGROUNDLOCKTIMEOUT, 0, Timeout, SPIF_SENDCHANGE);
    }
}

From my app, I do the following when a timer ticks and finds that one of the background windows must be activated:

IntPtr originalWHwnd = GetForegroundWindow();   //To keep the handle of the window in which the user is currently working.

/* Let's say that window with handle "hWnd" must be visible now: */
activateWindow(hWnd);  //It works in Vista and XP: brings the window to foreground.

/*
    Here I do the stuff with the window "hWnd":
     - move the mouse somewhere,
     - click somewhere else...
     */

/* Finally I want to bring back the original window: */
activateWindow(originalWHwnd);  //It does not work on Vista; it does on XP.

That code still works on Windows XP, but still doesn't work on Vista: step 4 will not bring to foreground the first window.

Please, could you enlighten me?

Thanks in advance.

musefan17-Jul-09 1:20

musefan

17-Jul-09 1:20

So it works the first time you call it, but not the second time? hmmm... does not sound logical to me.

perhaps you have an issue elsewhere. maybe your GetForegroundWindow() is not returning the correct handle (just an example)

Life goes very fast. Tomorrow, today is already yesterday.

verence33317-Jul-09 1:45

17-Jul-09 1:45

You're right, could be something like that. But why would it fail only in Vista? I will debug it carefully when I can...

Simon P Stevens17-Jul-09 1:24

Simon P Stevens

17-Jul-09 1:24

The thing you have to remember is that the user should always be in control of the PC. In the good old days of windows 95, any app could bring itself to the front to alert the user. After a while this created all kinds of problems because you would be typing away and other apps would be grabbing focus all over the place and interrupting your typing, (often catching your key presses and causing unexpected behaviour)

The powers that be realised that this was wrong and decided to fix it. So they changed things so apps couldn't bring them selves to the front, and instead just flashed the toolbar.

this is great except there are some people that still want to slam their apps to the foreground, so these people started working out ways round the restrictions (like the one you have used). Microsoft take note of these hacks and fix the problem for the next version.

The short story is that you should never be forcefully taking focus from what the user is doing. That is why vista doesn't support it. Instead you should flash the toolbar and wait for the user to respond to your app.

Simon

verence33317-Jul-09 1:58

17-Jul-09 1:58

Thanks, Simon. Yes, these days I've read some explanations like yours and I knew why Microsoft made these changes.

I don't want to bring my own app to the foreground, but windows that were already open (by the user himself) before my app run. It's just as if the user would have pressed Alt+Tab and then interacted with those windows, only that my app automates this.

And the fact is that, if I want the window to be active, I can, in a messy way. As a last resort, I could set foreground window, and then move the mouse down and click the taskbar to activate the flashing window or something. But I don't think that's the way things must be done, and Microsoft should allow programmers to easily bring windows to the front (because, if not, they will do it anyway but in the hard way).

Luc Pattyn17-Jul-09 1:33

Luc Pattyn

17-Jul-09 1:33

Hi,

I did some automation to have two apps exchange some data. It used the whole range of Get/SetForeGroundWindow, SendKeys, SendInput, and what have you. It runs fine on both XP and Vista, never had any trouble with it. I did develop on Vista (my main machine runs Vista, and I like it!), and it worked on XP right away. I just don't know if the reverse would also have worked right away.

I did implement automatic retries and a range of checks, e.g. after each SetForeGroundWindow, I wait some msec, then check by reading the title of the result of GetForeGroundWindow, to make absolutely sure I wasn't sending keyboard/mouse actions to the wrong app (the user, not me, might be touching the system while this automation is running).

BTW: I did not use AttachThreadInput, I hadn't even heard of it.

Smile | :)

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verence33317-Jul-09 2:01

17-Jul-09 2:01

Thank you, I'll implement retries as well, maybe the problem can be solved with some delays here and there and SetForegroundWindow works after all...

I'll let you all know when I can test it, maybe next week. Thanks!

verence33319-Jul-09 20:09

19-Jul-09 20:09

Well, now it works. I added some delays and a retries policy (as you suggested), and now the above code works on both Windows XP and Vista.

Thank you all!

Error

john563217-Jul-09 0:32

17-Jul-09 0:32

Hi,

I am trying to traverse all email from Inbox Folder of outlook but after 672 email I got an exception "Spacified cast is not valid" Even Inbox has more than 1600 emails.

My code is like

Microsoft.Office.Interop.Outlook.Items MyItem=mItem.Items;
MyItem.Sort("Received", false);
foreach(Microsoft.Office.Interop.Outlook.MailItem item in MyItem)
{
....
....
}

Please tell me what is the problem?

0x3c017-Jul-09 0:35

0x3c0

17-Jul-09 0:35

Chances are that you've got something in your Received folder that isn't a MailItem. When you iterate through the items, you do an implicit cast. Change the declaration of item to a base class, and check if it's a MailItem in the loop. If it is, cast and work with it as normal. If it isn't, continue iterating

Between the idea
And the reality
Between the motion
And the act
Falls the Shadow

john563217-Jul-09 0:55

17-Jul-09 0:55

Please tell me how to do that?

0x3c017-Jul-09 1:05

0x3c0

17-Jul-09 1:05

It appears that Outlook's interface isn't type safe. Yuck. Try something like this:

foreach(object item in MyItem)
{
    if(item is Microsoft.Office.Interop.Outlook.MailItem)
    {
        ...
        ...
    }
}

Between the idea
And the reality
Between the motion
And the act
Falls the Shadow

john563217-Jul-09 1:35

17-Jul-09 1:35

Thank you for idea but not able to traverse MyItem...

0x3c017-Jul-09 1:44

0x3c0

17-Jul-09 1:44

But the code in your original post does that. All that I changed in the foreach loop was the type of the variable. You have just replaced the foreach loop (not the first two lines of your code), right?

Between the idea
And the reality
Between the motion
And the act
Falls the Shadow

john563217-Jul-09 2:33