I have a project where I have Main mdi form which is of Type Ribbon.
There is TabbedMDIManager control on that MainForm which RibbonStyle is set to TouchStyle.
I have a separate child form which is inherits from MetroForm.
I have combboxadv1 set to Metro style on that child form. comboboxadv1 is empty and doesn't contain items.
When I run application and put two or more ChildForms in TabbedMDIManager.
After that I click for example on second tab to activate form. After that comboboxadv1 gets focus and become active (text within becomes blue).
After that I click on Close button on MainForm to close whole application and than following error message is thrown:
An unhandled exception of type 'System.NullReferenceException' occurred in Syncfusion.Shared.Base.dll
Additional information: Object reference not set to an instance of an object.
System.NullReferenceException was unhandled
Message=Object reference not set to an instance of an object.
at Syncfusion.Windows.Forms.Tools.ComboDropDown.InitDropDownButton(DropDownButton ddButton)
at Syncfusion.Windows.Forms.Tools.ComboBoxBase.OnHandleCreated(EventArgs e)
at System.Windows.Forms.Control.WmCreate(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at Syncfusion.Windows.Forms.Tools.ComboDropDown.WndProc(Message& m)
at Syncfusion.Windows.Forms.Tools.ComboBoxAdv.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
If I set Style to comboBoxAdv1 to Default then app closes without error message.
Is this normal behaviour?