Hello, I met the error that I don't know how to address.

[steven1536796418]

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I met the error that " Invalid parent form. When using DockingMdi or SystemMdi document style, the DockPanel control must be the child control of the main MDI container form.", however, I have set the mainform "ismdicontainer" = True, and the panel "documentstyle" = DockingMdi.

What to be noted is that, when I don't move the childform( the childform is hidden), this error won't appear, but when I move the childform from the hidden state, this error will appear. May you help to find what is happening with this error? Thanks.

[lextm]

I hope I can explain further, but "DockPanel control must be the child control of the main MDI container form" answers you. Learn to use the Document Outline window of Visual Studio, because it tells you the relationship among the controls,

http://geekswithblogs.net/pavelka/archive/2006/11/20/VisualStudioAndTheDocumentOutlineWindow.aspx

[steven1536796418]

I hope I can explain further, but "DockPanel control must be the child control of the main MDI container form" answers you. Learn to use the Document Outline window of Visual Studio, because it tells you the relationship among the controls,

http://geekswithblogs.net/pavelka/archive/2006/11/20/VisualStudioAndTheDocumentOutlineWindow.aspx

Thank for your reply, I have use the Document Outline of the vs, and the panel is actually the child control of the main MDI, maybe some other factors cause this error? I use the dockpanel by adding the dll, inculding the Docking and ThemeVS2015 .dll, however, I can't change the theme of panel in the beginning, and I change it with the code inside. Sorry, I am new to this, but any thing will help. Thanks.

[lextm]

In vNext release we are going to change the default docking style away from MDI. That should resolve such issues, as most people never care about MDI.