FormMain.cs

using System;
using System.IO;
using System.Diagnostics;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Linq;

namespace DragForListary {
    public partial class FormMain : Form {
        string targetPath;
        FileInfo targetInfo;
        bool targetDir = false;
        bool targetExec = false;

        string[] dropped = null;

        bool Copy = true;
        bool Exec = false;

        public FormMain(string targetPath) {
            InitializeComponent();

            ClosePrompt();

            this.targetPath = targetPath;
            label1.Text = targetPath;

            targetInfo = new FileInfo(targetPath);
            targetDir = targetInfo.Attributes.HasFlag(FileAttributes.Directory);
            if (!targetDir) {
                var exec = Environment.GetEnvironmentVariable("PATHEXT")
                    .ToUpper().Split(';').ToList()
                    .Where(a => !String.IsNullOrEmpty(a))
                    .ToList();
                string ext = targetInfo.Extension.ToUpper();
                targetExec = exec.Contains(ext);
            }
        }

        private void FormMain_DragOver(object sender, DragEventArgs e) {
            if (targetExec && e.KeyState == 1) {              // LeftButton
                e.Effect = DragDropEffects.Link;
                this.Text = "Exec";
            } else if (e.KeyState == 5) {                     // LeftButton + Shift
                e.Effect = DragDropEffects.Move;
                this.Text = "Move";
            } else if (e.KeyState == 1 || e.KeyState == 9) {  // LeftButton + None/Ctrl
                e.Effect = DragDropEffects.Copy;
                this.Text = "Copy";
            } else {
                e.Effect = DragDropEffects.None;
                this.Text = "";
            }
        }

        private void FormMain_DragLeave(object sender, EventArgs e) {
            this.Text = "";
        }

        private void FormMain_DragDrop(object sender, DragEventArgs e) {
            this.Text = "";
            dropped = (string[])e.Data.GetData(DataFormats.FileDrop);
            if (dropped != null) {
                if (targetExec && e.KeyState == 0) {
                    Exec = true;
                } else if (e.KeyState == 4) {     // Shift
                    Exec = false;
                    Copy = false;
                }
                timer.Enabled = true;
            }
        }

        private void Timer_Tick(object sender, EventArgs e) {
            timer.Enabled = false;
            if (!targetDir && !targetInfo.Exists) return;

            if (Exec) {
                ProcessStartInfo ps = new ProcessStartInfo(targetPath);
                ps.UseShellExecute = true;
                ps.CreateNoWindow = false;
                ps.Arguments = " \"" + string.Join("\" \"", dropped) + "\"";
                Process.Start(ps);
            } else {
                SHFILEOPSTRUCT pm = new SHFILEOPSTRUCT();
                pm.fFlags = FILEOP_FLAGS.FOF_ALLOWUNDO;
                pm.pFrom = string.Join("\0", dropped) + "\0\0";
                pm.wFunc = Copy ? wFunc.FO_COPY : wFunc.FO_MOVE;

                if (targetDir) {
                    pm.pTo = targetInfo.FullName;
                } else {
                    pm.pTo = targetInfo.DirectoryName;
                }

                SHFileOperation(pm);
            }
        }

        void ClosePrompt() {
            var hwnd = FindWindow("Listary_WidgetWin_0", "");
            if (hwnd != IntPtr.Zero) PostMessage(hwnd, 16, IntPtr.Zero, IntPtr.Zero);
        }

        [DllImport("user32.dll")]
        static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
        static extern int SHFileOperation(SHFILEOPSTRUCT lpFileOp);

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        private class SHFILEOPSTRUCT {
            public IntPtr hwnd;
            public wFunc wFunc;
            public string pFrom;
            public string pTo;
            public FILEOP_FLAGS fFlags;
            public bool fAnyOperationsAborted;
            public IntPtr hNameMappings;
            public string lpszProgressTitle;
        }

        private enum wFunc {
            FO_MOVE = 0x1,
            FO_COPY = 0x2,
            FO_DELETE = 0x3,
            FO_RENAME = 0x4
        }

        private enum FILEOP_FLAGS {
            FOF_MULTIDESTFILES = 0x1,
                //The pTo member specifies multiple destination files (one for each source file) rather than one directory where all source files are to be deposited.
            FOF_CONFIRMMOUSE = 0x2,
                //Not currently used.
            FOF_SILENT = 0x4,
                //Do not display a progress dialog box.
            FOF_RENAMEONCOLLISION = 0x8,
                //Give the file being operated on a new name in a move, copy, or rename operation if a file with the target name already exists.
            FOF_NOCONFIRMATION = 0x10,
                //Respond with "Yes to All" for any dialog box that is displayed.
            FOF_WANTMAPPINGHANDLE = 0x20,
                //If FOF_RENAMEONCOLLISION is specified and any files were renamed, assign a name mapping object containing their old and new names to the hNameMappings member.
            FOF_ALLOWUNDO = 0x40,
                //Preserve Undo information, if possible. If pFrom does not contain fully qualified path and file names, this flag is ignored.
            FOF_FILESONLY = 0x80,
                //Perform the operation on files only if a wildcard file name (*.*) is specified.
            FOF_SIMPLEPROGRESS = 0x100,
                //Display a progress dialog box but do not show the file names.
            FOF_NOCONFIRMMKDIR = 0x200,
                //Do not confirm the creation of a new directory if the operation requires one to be created.
            FOF_NOERRORUI = 0x400,
                //Do not display a user interface if an error occurs.
            FOF_NOCOPYSECURITYATTRIBS = 0x800,
                //Do not copy the security attributes of the file.
            FOF_NORECURSION = 0x1000,
                //Only operate in the local directory. Don't operate recursively into subdirectories.
            FOF_NO_CONNECTED_ELEMENTS = 0x2000,
                //Do not move connected files as a group. Only move the specified files.
            FOF_WANTNUKEWARNING = 0x4000,
                //Send a warning if a file is being destroyed during a delete operation rather than recycled. This flag partially overrides FOF_NOCONFIRMATION.
            FOF_NORECURSEREPARSE = 0x8000,
                //Treat reparse points as objects, not containers.
        }
    }
}