Null Ref Exception in docking code

[Gus Felderhoff]

With the following code, I am able to create a situation in which I get a null reference exception. To reproduce, paste this into a load event on a form.

Control ctrl1 = new ListView();
Control ctrl2 = new ListView();
Control ctrl3 = new ListView();
Control ctrl4 = new ListView();
Control ctrl5 = new ListView();

m_DockingManager = new DockingManager();

m_DockingManager.BeginInit();

m_DockingManager.HostForm = this;
m_DockingManager.DockToFill = true;

m_DockingManager.DockControl(ctrl1, this, DockingStyle.Fill, 200);
m_DockingManager.DockControl(ctrl2, ctrl1, DockingStyle.Right, 200);
m_DockingManager.DockControl(ctrl3, ctrl2, DockingStyle.Tabbed, 200);
m_DockingManager.DockControl(ctrl4, ctrl2, DockingStyle.Tabbed, 200);
m_DockingManager.DockControl(ctrl5, ctrl1, DockingStyle.Bottom, 200);
m_DockingManager.SetDockLabel(ctrl1, "ctrl1");
m_DockingManager.SetDockLabel(ctrl2, "ctrl2");
m_DockingManager.SetDockLabel(ctrl3, "ctrl3");
m_DockingManager.SetDockLabel(ctrl4, "ctrl4");
m_DockingManager.SetDockLabel(ctrl5, "ctrl5");

m_DockingManager.EndInit();

Run the app.
Double click on the pane labeled "ctrl4" and it undocks.
Double click on it again and it will cause the exception.

I am using version 3.0.1.0. Any help would be greatly appreciated.

[Administrator]

Hi Gus,

There were a few issues in v3.0.1.0 that caused DockingManager to throw exceptions. These fixes, along with a number of other fixes, are included in v3.2.1.0 and I would recommend upgrading if possible.

Regards,
Gregory Austin
Syncfusion Inc.

[Gus Felderhoff]

Thank you Gregory. I did as you recommended, and no longer get the exception. Although, now when I follow the steps outlined in the original post, the individual panes that were tabbed before undocking are now untabbed when redocking. Is there a way around this?

[Gus Felderhoff]

In addition, now when I first bring up my application, the code posted above does not display any windows on my form.

[Gus Felderhoff]

I have found a work around in which everything works as expected. I have used a DockingClientPanel for the ''main'' panel within my form.

Control ctrl1 = new ListView();
Control ctrl2 = new ListView();
Control ctrl3 = new ListView();
Control ctrl4 = new ListView();
Control ctrl5 = new ListView();
DockingClientPanel panel;

this.components = new System.ComponentModel.Container();

m_DockingManager = new DockingManager();

m_DockingManager.BeginInit();

panel = new DockingClientPanel();
panel.SizeToFit = true;
this.Controls.Add(panel);

m_DockingManager.HostForm = this;
m_DockingManager.ThemesEnabled = true;

panel.Size = this.ClientSize;
ctrl1.Dock = DockStyle.Fill;
panel.Controls.Add(ctrl1);

m_DockingManager.DockControl(ctrl2, this, DockingStyle.Right, 200);
m_DockingManager.DockControl(ctrl3, ctrl2, DockingStyle.Tabbed, 200);
m_DockingManager.DockControl(ctrl4, ctrl2, DockingStyle.Tabbed, 200);
m_DockingManager.DockControl(ctrl5, this, DockingStyle.Bottom, 200);
m_DockingManager.SetDockLabel(ctrl2, "ctrl2");
m_DockingManager.SetDockLabel(ctrl3, "ctrl3");
m_DockingManager.SetDockLabel(ctrl4, "ctrl4");
m_DockingManager.SetDockLabel(ctrl5, "ctrl5");

m_DockingManager.EndInit();