"Frank Stegerwald" <stegerwald@newsgroup.nospam> wrote in message
news:%23d3Gvg1OFHA.2144@TK2MSFTNGP09.phx.gbl...
> Hi,
>
> i have a Windows Form (Splashscreen) that runs on
> a seperate thread until my main app is up and running.
>
> This form has its FrameBorderStyle set to "None".
> How can I prevent this Form from beeing displayed in the
> "ALT+TAB" list?
>
> Any help will be greatly appreciated
>
> Frank Stegerwald

Jeffrey Tan[MSFT] wrote:
> Hi Frank,
>
> Thanks for your post!!
>
> I think Eric has provided you half of the solution :-)
>
> Actually, whether a Window(In .Net, this is called Form) will appear in
> Alt+Tab list can be determined by its extended window style. For a detailed
> description of "Extended Window Styles", please refer to:
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcmfc98/htm
> l/_mfc_extended_window_styles.asp
>
> In the above reference, you will see that:
> WS_EX_APPWINDOW: Forces a top-level window onto the taskbar when the window
> is visible.
> WS_EX_TOOLWINDOW: Creates a tool window, which is a window intended to be
> used as a floating toolbar. A tool window has a title bar that is shorter
> than a normal title bar, and the window title is drawn using a smaller
> font. A tool window does not appear in the task bar or in the window that
> appears when the user presses ALT+TAB.
>
> So if we get rid of a window(Form)'s WS_EX_APPWINDOW style and then apply
> WS_EX_TOOLWINDOW to it, we can get what we want. In .Net a Form's style and
> extended style can be changed through overriding CreateParams property,
> like below:
>
> //Suppose Form2 is the splash window
> private const int WS_EX_TOOLWINDOW= 0x00000080;
> private const int WS_EX_APPWINDOW=0x00040000;
> protected override CreateParams CreateParams
> {
> get
> {
> CreateParams cp=base.CreateParams;
> cp.ExStyle=cp.ExStyle&(~WS_EX_APPWINDOW);
> cp.ExStyle=cp.ExStyle|WS_EX_TOOLWINDOW;
> return cp;
> }
> }
>
> //In Main app(Form1)
> public Form1()
> {
> Thread t=new Thread(new ThreadStart(ThreadProc));
> t.Start();
> System.Threading.Thread.Sleep(5000);
> InitializeComponent();
> }
>
> private void ThreadProc()
> {
> Form2 f=new Form2();
> f.FormBorderStyle=FormBorderStyle.None;
> Application.Run(f);
> }
>
> Why I say Eric gives you the half solution? Because .Net encapsulate
> WS_EX_APPWINDOW style as ShowInTaskbar property, so if we set
> ShowInTaskbar=false, we can get rid of this line:
> cp.ExStyle=cp.ExStyle&(~WS_EX_APPWINDOW). They are the same effect.
>
> At last, if you want to hide an already existed window from Alt+Tab list,
> you can p/invoke SetWindowLong/GetWindowLong Win32 Api to change it
> extended window style.
>
> The above code works well on my side. Hope this helps.
>
> Best regards,
> Jeffrey Tan
> Microsoft Online Partner Support
> Get Secure! - www.microsoft.com/security
> This posting is provided "as is" with no warranties and confers no rights.