Windows Forms FAQ resources

11. Windows Forms Mouse Handling

11.6 How can I drag a window if it doesn't have a title bar or border?

You can drag such a window by using Win32 APIs to switch the mouse hit to WM_NCLBUTTONDOWN. The code below will allow you to drag by mousing down anywhere in the form's clientarea as long as you don't hit a child control on the form.

using System.Runtime.InteropServices;

............

public const int WM_NCLBUTTONDOWN = 0xA1;

public const int HTCAPTION = 0x2;

[DllImportAttribute ("user32.dll")]

public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);

[DllImportAttribute ("user32.dll")]

public static extern bool ReleaseCapture();

private void Form2_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)

{

ReleaseCapture();

SendMessage(Handle, WM_NCLBUTTONDOWN, HTCAPTION, 0);

}

Here is a solution posed by Jacob Grass (Abiliti Solutions) that does not rely on InteropServices.

Private blnMoving As Boolean = False

Private MouseDownX As Integer

Private MouseDownY As Integer

Private Sub Form1_MouseDown(ByVal sender As Object, _

ByVal e As System.Windows.Forms.MouseEventArgs) Handles Form1.MouseDown

If e.Button = MouseButtons.Left Then

blnMoving = True

MouseDownX = e.X

MouseDownY = e.Y

End If

End Sub

Private Sub Form1_MouseUp(ByVal sender As Object, _

ByVal e As System.Windows.Forms.MouseEventArgs) Handles Form1.MouseUp

If e.Button = MouseButtons.Left Then

blnMoving = False

End If

End Sub

Private Sub Form1_MouseMove(ByVal sender As Object, _

ByVal e As System.Windows.Forms.MouseEventArgs) Handles Form1.MouseMove

If blnMoving Then

Dim temp As Point = New Point()

temp.X = Form1.Location.X + (e.X - MouseDownX)

temp.Y = Form1.Location.Y + (e.Y - MouseDownY)

Form1.Location = temp

End If

End Sub