C# WinForm Making a TopBar App

Question

I want to make a TopBar app for my increase productivity. I have designed an TopBar App on Visual Studio 2022 using C# but I don't know and I can not find any way to solve 3 problems.

1- My program's location is 0,0 so Left-Top and size is Screen.PrimaryScreen.Bounds.Width, 24px I decided. But Program is not resizing as 24px. Maybe minimum limit is 60-100px for width for a program. I want to make program's size ScreenWidth and 24px height.

2- I don't want to see my program in Alt-Tab switcher and taskbar. ShowInTaskbar = false is not working. Always showing in taskbar and Alt-Tab.

3- All programs coming behind to my program as browser tabs. My mean is When I'm running my program, browser tabs are behind my program. I want to make them under program. As MAC OS or some topbar programs like as MyDockFinder.

1. I can not set my program's width less than minimum size, I want to set it 24px.
2. I want to hide my program from Alt-Tab switcher and taskbar.

3- I want to set all windows and desktop icons under my program.

I hope I explained my problems enough.

Answer 1

You can use an AppBar

Minimal test with an AppBar at Top of the screen, 24 pixels height
For this test, don't forget to add a Button to close the window to remove the AppBar space with ABM_REMOVE

public partial class Form1 : Form  
{  
    [DllImport("Shell32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern uint SHAppBarMessage(uint dwMessage, ref APPBARDATA pData);  

    public const int ABM_NEW = 0x00000000;  
    public const int ABM_REMOVE = 0x00000001;  
    public const int ABM_QUERYPOS = 0x00000002;  
    public const int ABM_SETPOS = 0x00000003;  
    public const int ABM_GETSTATE = 0x00000004;  
    public const int ABM_GETTASKBARPOS = 0x00000005;  
    public const int ABM_ACTIVATE = 0x00000006;  // lParam == TRUE/FALSE means activate/deactivate  
    public const int ABM_GETAUTOHIDEBAR = 0x00000007;  
    public const int ABM_SETAUTOHIDEBAR = 0x00000008;  // this can fail at any time.  MUST check the result  
                                                       // lParam = TRUE/FALSE  Set/Unset  
                                                       // uEdge = what edge  
    public const int ABM_WINDOWPOSCHANGED = 0x0000009;  
    public const int ABM_SETSTATE = 0x0000000a;  
    public const int ABM_GETAUTOHIDEBAREX = 0x0000000b; // multimon aware autohide bars  
    public const int ABM_SETAUTOHIDEBAREX = 0x0000000c;  

    // these are put in the wparam of callback messages  
    public const int ABN_STATECHANGE = 0x0000000;  
    public const int ABN_POSCHANGED = 0x0000001;  
    public const int ABN_FULLSCREENAPP = 0x0000002;  
    public const int ABN_WINDOWARRANGE = 0x0000003; // lParam == TRUE means hide  

    // flags for get state  
    public const int ABS_AUTOHIDE = 0x0000001;  
    public const int ABS_ALWAYSONTOP = 0x0000002;  

    public const int ABE_LEFT    =    0;  
    public const int ABE_TOP     =    1;  
    public const int ABE_RIGHT   =    2;  
    public const int ABE_BOTTOM  =    3;  

    [StructLayout(LayoutKind.Sequential)]  
    public struct APPBARDATA  
    {  
        public uint cbSize;  
        public IntPtr hWnd;  
        public uint uCallbackMessage;  
        public uint uEdge;  
        public RECT rc;  
        public IntPtr lParam; // message specific  
    }  

    [StructLayout(LayoutKind.Sequential)]  
    public struct RECT  
    {  
        public int left;  
        public int top;  
        public int right;  
        public int bottom;  
        public RECT(int Left, int Top, int Right, int Bottom)  
        {  
            left = Left;  
            top = Top;  
            right = Right;  
            bottom = Bottom;  
        }  
    }  

    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern uint RegisterWindowMessage(string lpString);  

    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);  

    public const int WS_EX_TOPMOST = 0x00000008;  
    public const int WS_EX_TOOLWINDOW = 0x00000080;  
    public const int WS_EX_APPWINDOW = 0x00040000;  
      

    public Form1()  
    {  
        InitializeComponent();  
        this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;  
        this.button1.Top = 0;  
    }  

    protected override CreateParams CreateParams  
    {  
        get  
        {  
            CreateParams cp = base.CreateParams;  
            cp.ExStyle |= (WS_EX_TOOLWINDOW | WS_EX_TOPMOST);  
            cp.ExStyle -= (WS_EX_APPWINDOW);  
            return cp;  
        }  
    }  

    uint nAppBarCallBackMessage = 0;  

    private void Form1_Load(object sender, EventArgs e)  
    {  
        APPBARDATA abd = new APPBARDATA();  
        abd.cbSize = (uint)Marshal.SizeOf(abd);  
        abd.hWnd = this.Handle;  
        nAppBarCallBackMessage = RegisterWindowMessage("Test CallBack");             
        abd.uCallbackMessage = nAppBarCallBackMessage;  
        SHAppBarMessage(ABM_NEW, ref abd);  
        int nX = 0, nY = 0;  
        int nWidth = Screen.PrimaryScreen.Bounds.Width, nHeight = 24;  
        abd.rc.left = nX;  
        abd.rc.top = nY;  
        abd.rc.right = nWidth;  
        abd.rc.bottom = nHeight;  
        abd.uEdge = ABE_TOP;  

        // In case program exited without ABM_REMOVE, BP in SHAppBarMessage, then stop to remove the AppBar space  
        // abd.rc.bottom = 0;  
        SHAppBarMessage(ABM_SETPOS, ref abd);            

        MoveWindow(this.Handle, nX, nY, nWidth, nHeight, true);  
    }  

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)  
    {  
        APPBARDATA abd = new APPBARDATA();  
        abd.hWnd = this.Handle;  
        SHAppBarMessage(ABM_REMOVE, ref abd);  
    }  

    private void button1_Click(object sender, EventArgs e)  
    {  
        this.Close();  
    }  
}