C# 窗口拖动尺寸大小鼠标闪动，拖动不方便

这种情况可能是因为窗口的边框样式设置不当所导致的。你可以尝试在窗口加载时，通过代码将窗口的边框样式设置为None，然后自己实现窗口的拖动与缩放功能。

具体实现可以参考以下代码：

public partial class MainForm : Form
{
    private const int WM_NCHITTEST = 0x0084;
    private const int HTLEFT = 10;
    private const int HTRIGHT = 11;
    private const int HTTOP = 12;
    private const int HTTOPLEFT = 13;
    private const int HTTOPRIGHT = 14;
    private const int HTBOTTOM = 15;
    private const int HTBOTTOMLEFT = 16;
    private const int HTBOTTOMRIGHT = 17;

    private const int BORDER_WIDTH = 5;

    public MainForm()
    {
        InitializeComponent();

        // 设置窗口的边框样式为None
        this.FormBorderStyle = FormBorderStyle.None;
    }

    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);

        if (m.Msg == WM_NCHITTEST)
        {
            Point point = this.PointToClient(new Point(m.LParam.ToInt32() & 0xffff, m.LParam.ToInt32() >> 16));

            if (point.X <= BORDER_WIDTH && point.Y <= BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTTOPLEFT;
            }
            else if (point.X >= this.ClientSize.Width - BORDER_WIDTH && point.Y <= BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTTOPRIGHT;
            }
            else if (point.X <= BORDER_WIDTH && point.Y >= this.ClientSize.Height - BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTBOTTOMLEFT;
            }
            else if (point.X >= this.ClientSize.Width - BORDER_WIDTH && point.Y >= this.ClientSize.Height - BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTBOTTOMRIGHT;
            }
            else if (point.X <= BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTLEFT;
            }
            else if (point.X >= this.ClientSize.Width - BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTRIGHT;
            }
            else if (point.Y <= BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTTOP;
            }
            else if (point.Y >= this.ClientSize.Height - BORDER_WIDTH)
            {
                m.Result = (IntPtr)HTBOTTOM;
            }
        }
    }
}

这段代码实现了窗口的边框拖动功能，当鼠标移动到窗口边缘时，鼠标的样式会改变，然后通过重写窗口的WndProc方法，实现窗口的拖动与缩放功能。