linear-app-launcher/Windows/Forms/TitlePanel.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace AppLauncher.Windows.Forms
{
    public partial class TitlePanel : UserControl
    {
        private bool isDragging = false;
        private Point windowOffset = new Point();

        public TitlePanel()
        {
            InitializeComponent();
        }

        protected override void OnParentBindingContextChanged(EventArgs e)
        {
            base.OnParentBindingContextChanged(e);

            if (this.Parent != null)
            {
                if (this.Parent.GetType() == typeof(MainForm))
                {
                    pictureBox1.MouseDown += parentForm_MouseDown;
                    pictureBox1.MouseUp += parentForm_MouseUp;
                    pictureBox1.MouseMove += parentForm_MouseMove;
                }
            }
        }

        [Category("Appearance"), Browsable(true)]
        public string TitleText
        {
            get => label1.Text;
            set => label1.Text = value;
        }

        protected void parentForm_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button != MouseButtons.Left)
            {
                return;
            }

            isDragging = true;
            windowOffset = e.Location;
        }

        protected void parentForm_MouseUp(object sender, MouseEventArgs e)
        {
            isDragging = false;
        }

        protected void parentForm_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDragging)
            {
                Point pos = this.PointToScreen(e.Location);

                int y = Math.Max((pos.Y - windowOffset.Y), Screen.PrimaryScreen.WorkingArea.Y);
                y = Math.Min(y, (Screen.PrimaryScreen.WorkingArea.Y + Screen.PrimaryScreen.WorkingArea.Height) - this.Height);

                this.Parent.Location = new Point(Screen.PrimaryScreen.WorkingArea.X, y);
            }
        }

    }
}