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using System;
using System.Windows.Forms;
namespace WeifenLuo.WinFormsUI.Docking
{
// Inspired by Chris Sano's article:
// http://msdn.microsoft.com/smartclient/default.aspx?pull=/library/en-us/dnwinforms/html/colorpicker.asp
// In Sano's article, the DragForm needs to meet the following criteria:
// (1) it was not to show up in the task bar;
// ShowInTaskBar = false
// (2) it needed to be the top-most window;
// TopMost = true
// (3) its icon could not show up in the ALT+TAB window if the user pressed ALT+TAB during a drag-and-drop;
// FormBorderStyle = FormBorderStyle.None;
// Create with WS_EX_TOOLWINDOW window style.
// Compares with the solution in the artile by setting FormBorderStyle as FixedToolWindow,
// and then clip the window caption and border, this way is much simplier.
// (4) it was not to steal focus from the application when displayed.
// User Win32 ShowWindow API with SW_SHOWNOACTIVATE
// In addition, this form should only for display and therefore should act as transparent, otherwise
// WindowFromPoint will return this form, instead of the control beneath. Need BOTH of the following to
// achieve this (don't know why, spent hours to try it out :( ):
// 1. Enabled = false;
// 2. WM_NCHITTEST returns HTTRANSPARENT
public class DragForm : Form
{
public DragForm()
{
FormBorderStyle = FormBorderStyle.None;
ShowInTaskbar = false;
SetStyle(ControlStyles.Selectable, false);
Enabled = false;
TopMost = true;
}
protected override CreateParams CreateParams
{
get
{
CreateParams createParams = base.CreateParams;
createParams.ExStyle |= (int)(Win32.WindowExStyles.WS_EX_NOACTIVATE | Win32.WindowExStyles.WS_EX_TOOLWINDOW);
return createParams;
}
}
protected override void WndProc(ref Message m)
{
if (m.Msg == (int)Win32.Msgs.WM_NCHITTEST)
{
m.Result = (IntPtr)Win32.HitTest.HTTRANSPARENT;
return;
}
base.WndProc(ref m);
}
//The form can be still activated by explicity calling Activate
protected override bool ShowWithoutActivation
{
get { return true; }
}
public virtual void Show(bool bActivate)
{
Show();
if (bActivate)
Activate();
}
}
}
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