Hello,
the attached sample demonstrates error conditions that occur when two independent (and not linked to each other) docking managers are used in an application. One docking manager handles dockable views in the main window. Yet another docking manager handles exactly two sub-views (view #2 and view #3) in a view docked in the main window (view #1). It is worth of mentioning that either view #2 or view #3 is auto-hidden on load (for the sake of argument, let''s say it is view #2), and the docking manager that works within view #1 confines has "Dock with Fill Style" property enabled.
Now, everything works fine (e.g. view #1 can be undocked from its default location, and re-docked somewhere else) until the size of view #2 (the one that is auto-hidden on load) changes. While the application appears to be performing normally, it is no longer the case. View #1 can no longer be re-docked within its docking manager constraints without causing a NullReferenceException, like the one below:
System.NullReferenceException: Object reference not set to an instance of an object.
at Syncfusion.Windows.Forms.Tools.WhidbeyDragProvider.UpdateDragControlPosition(Point ptscreen)
at Syncfusion.Windows.Forms.Tools.WhidbeyDragProvider.HostControl_Move(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnMove(EventArgs e)
at System.Windows.Forms.Control.OnLocationChanged(EventArgs e)
at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height, Int32 clientWidth, Int32 clientHeight)
at System.Windows.Forms.Control.UpdateBounds()
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.UserControl.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
************** Loaded Assemblies **************
Syncfusion.Tools.Windows
Assembly Version: 4.202.0.37
Win32 Version: 4.202.0.37
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/Syncfusion.Tools.Windows/4.202.0.37__3d67ed1f87d44c89/Syncfusion.Tools.Windows.dll
----------------------------------------
Syncfusion.Shared.Base
Assembly Version: 4.202.0.37
Win32 Version: 4.202.0.37
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/Syncfusion.Shared.Base/4.202.0.37__3d67ed1f87d44c89/Syncfusion.Shared.Base.dll
----------------------------------------
Syncfusion.Core
Assembly Version: 4.202.0.37
Win32 Version: 4.202.0.37
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/Syncfusion.Core/4.202.0.37__632609b4d040f6b4/Syncfusion.Core.dll
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Regards,
Dmitry.
DockingFailure.zip