Thomas Levesque's .NET blog Tips, tricks and thoughts about .NET development

Here’s a piece of code I wrote a while ago, I just thought it could be useful for WinForms developers…

In WPF, there is a very handy method to move a window with no borders : Window.DragMove. It can be used like that :

        private void Window_MouseDown(object sender, MouseButtonEventArgs e)
        {
            this.DragMove();
        }

When you call this method, the window is moved with the mouse until the button is released. It could hardly be simpler 😉

Unfortunately, this method only exists in WPF, and a majority of developers are still working with Windows Forms. So I came up with a solution to use a similar technique in Windows Forms, with a few improvements :

• Usable on any control, not only a window
• No need to explicitly handle the MouseDown event
• Form designer integration, using a IExtenderProvider

My solution consists of the following items :

• a static DragMoveExtensions class which provides extension methods for the Control class (easily convertible to regular static methods for use with C# 2)
• a DragMoveProvider component, which implements IExtenderProvider to add a new EnableDragMove property to controls

There are several ways to use this solution, pick the one that best suits your needs :

• The simplest, which requires no coding at all : in design mode, drop a DragMoveProvider on the Form, and set the EnableDragMove property to true on the Form or control


DragMoveProvider

• The closest to WPF’s DragMove : in the handler of the MouseDown event, call the DragMove extension method on the Form or control to move

        private void label2_MouseDown(object sender, MouseEventArgs e)
        {
            label2.DragMove();
        }

• The most flexible : call the EnableDragMove extension method on the Form or control to move (no event handling needed).

        private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            this.EnableDragMove(checkBox1.Checked);
        }

The attached Visual Studio solution contains the WinFormsDragMove library, and a test project to demonstrate the various ways to use this library. A C#2-compatible version of these projects is also included.

Download source