[聚合问答] Show a Form without stealing focus?

Hmmm, isn't simply overriding Form.ShowWithoutActivation enough?

protected override bool ShowWithoutActivation
{
  get { return true; }
}

And if you don't want the user to click this notification window either, you can override CreateParams:

protected override CreateParams CreateParams
{
  get
  {
    CreateParams baseParams = base.CreateParams;

    const int WS_EX_NOACTIVATE = 0x08000000;
    const int WS_EX_TOOLWINDOW = 0x00000080;
    baseParams.ExStyle |= ( int )( WS_EX_NOACTIVATE | WS_EX_TOOLWINDOW );

    return baseParams;
  }
}

Stolen from PInvoke.net's ShowWindow method:

private const int SW_SHOWNOACTIVATE = 4;
private const int HWND_TOPMOST = -1;
private const uint SWP_NOACTIVATE = 0x0010;

[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
static extern bool SetWindowPos(
     int hWnd,             // Window handle
     int hWndInsertAfter,  // Placement-order handle
     int X,                // Horizontal position
     int Y,                // Vertical position
     int cx,               // Width
     int cy,               // Height
     uint uFlags);         // Window positioning flags

[DllImport("user32.dll")]
static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

static void ShowInactiveTopmost(Form frm)
{
     ShowWindow(frm.Handle, SW_SHOWNOACTIVATE);
     SetWindowPos(frm.Handle.ToInt32(), HWND_TOPMOST,
     frm.Left, frm.Top, frm.Width, frm.Height,
     SWP_NOACTIVATE);
}

(Alex Lyman answered this, I'm just expanding it by directly pasting the code. Someone with edit rights can copy it over there and delete this for all I care ;) )

If you're willing to use Win32 P/Invoke, then you can use the ShowWindow method (the first code sample does exactly what you want).

Doing this seems like a hack, but it seems to work:

this.TopMost = true;  // as a result the form gets thrown to the front
this.TopMost = false; // but we don't actually want our form to always be on top

Edit: Note, this merely raises an already created form without stealing focus.

The sample code from pinvoke.net in Alex Lyman/TheSoftwareJedi's answers will make the window a "topmost" window, meaning that you can't put it behind normal windows after it's popped up. Given Matias's description of what he wants to use this for, that could be what he wants. But if you want the user to be able to put your window behind other windows after you've popped it up, just use HWND_TOP (0) instead of HWND_TOPMOST (-1) in the sample.

This is what worked for me. It provides TopMost but without focus-stealing.

    protected override bool ShowWithoutActivation
    {
       get { return true; }
    }

    private const int WS_EX_TOPMOST = 0x00000008;
    protected override CreateParams CreateParams
    {
       get
       {
          CreateParams createParams = base.CreateParams;
          createParams.ExStyle |= WS_EX_TOPMOST;
          return createParams;
       }
    }

Remember to omit setting TopMost in Visual Studio designer, or elsewhere.

This is stolen, err, borrowed, from here (click on Workarounds):

https://connect.microsoft.com/VisualStudio/feedback/details/401311/showwithoutactivation-is-not-supported-with-topmost

In WPF you can solve it like this:

In the window put these attributes:

<Window
    x:Class="myApplication.winNotification"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="Notification Popup" Width="300" SizeToContent="Height"
  WindowStyle="None" AllowsTransparency="True" Background="Transparent" ShowInTaskbar="False" Topmost="True" Focusable="False" ShowActivated="False" >
</Window>

The last one attribute is the one you need ShowActivated="False".

Create and start the notification Form in a separate thread and reset the focus back to your main form after the Form opens. Have the notification Form provide an OnFormOpened event that is fired from the Form.Shown event. Something like this:

private void StartNotfication()
{
  Thread th = new Thread(new ThreadStart(delegate
  {
    NotificationForm frm = new NotificationForm();
    frm.OnFormOpen += NotificationOpened;
    frm.ShowDialog();
  }));
  th.Name = "NotificationForm";
  th.Start();
} 

private void NotificationOpened()
{
   this.Focus(); // Put focus back on the original calling Form
}

You can also keep a handle to your NotifcationForm object around so that it can be programmatically closed by the main Form (frm.Close()).

Some details are missing, but hopefully this will get you going in the right direction.

You might want to consider what kind of notification you would like to display.

If it's absolutely critical to let the user know about some event, using Messagebox.Show would be the recommended way, due to its nature to block any other events to the main window, until the user confirms it. Be aware of pop-up blindness, though.

If it's less than critical, you might want to use an alternative way to display notifications, such as a toolbar on the bottom of the window. You wrote, that you display notifications on the bottom-right of the screen - the standard way to do this would be using a balloon tip with the combination of a system tray icon.

I have something similar, and I simply show the notification form and then do

this.Focus();

to bring the focus back on the main form.

This works well:

[System.Runtime.InteropServices.DllImport("user32")]

public static extern long OpenIcon(long hwnd);

[System.Runtime.InteropServices.DllImport("user32")]

public static extern long SetForegroundWindow(long hwnd);


public static void ActivateInstance()
{

    long MyHndl = 0;

    long result = 0;

    Process objProcess = Process.GetCurrentProcess();

    MyHndl = objProcess.MainWindowHandle.ToInt32();

    result = OpenIcon(MyHndl); // Restore the program.

    result = SetForegroundWindow(MyHndl); // Activate the application.

    //System.Environment.Exit(0); // End the current instance of the application.

}

You can handle it by logic alone too, although I have to admit that the suggestions above where you end up with a BringToFront method without actually stealing focus is the most elegant one.

Anyhow, I ran into this and solved it by using a DateTime property to not allow further BringToFront calls if calls were made already recently.

Assume a core class, 'Core', which handles for example three forms, 'Form1, 2, and 3'. Each form needs a DateTime property and an Activate event that call Core to bring windows to front:

internal static DateTime LastBringToFrontTime { get; set; }

private void Form1_Activated(object sender, EventArgs e)
{
    var eventTime = DateTime.Now;
    if ((eventTime - LastBringToFrontTime).TotalMilliseconds > 500)
        Core.BringAllToFront(this);
    LastBringToFrontTime = eventTime;
}

And then create the work in the Core Class:

internal static void BringAllToFront(Form inForm)
{
    Form1.BringToFront();
    Form2.BringToFront();
    Form3.BringToFront();
    inForm.Focus();
}

On a side note, if you want to restore a minimized window to its original state (not maximized), use:

inForm.WindowState = FormWindowState.Normal;

Again, I know this is just a patch solution in the lack of a BringToFrontWithoutFocus. It is meant as a suggestion if you want to avoid the DLL file.

I don't know if this is considered as necro-posting, but this is what I did since I couln't get it working with user32's "ShowWindow" and "SetWindowPos" methods. And no, overriding "ShowWithoutActivation" doesn't work in this case since the new window should be always-on-top. Anyway, I created a helper method that takes a form as parameter; when called, it shows the form, brings it to the front and makes it TopMost without stealing the focus of the current window (apparently it does, but the user won't notice).

    [DllImport("user32.dll")]
    static extern IntPtr GetForegroundWindow();

    [DllImport("user32.dll")]
    static extern IntPtr SetForegroundWindow(IntPtr hWnd);

    public static void ShowTopmostNoFocus(Form f)
    {
        IntPtr activeWin = GetForegroundWindow();

        f.Show();
        f.BringToFront();
        f.TopMost = true;

        if (activeWin.ToInt32() > 0)
        {
            SetForegroundWindow(activeWin);
        }
    }