C#WinForm案例_父MDI窗体不重复打开子窗体

G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\bin\Debug\NotRepeatOpenFormDemo.exe.config G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\bin\Debug\NotRepeatOpenFormDemo.exe G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\bin\Debug\NotRepeatOpenFormDemo.pdb G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.csprojResolveAssemblyReference.cache G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.Properties.Resources.resources G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.csproj.GenerateResource.Cache G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.exe G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.pdb G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.FrmChild2.resources G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.FrmChild1.resources G:\Workspaces_training\NotRepeatOpenFormDemo\NotRepeatOpenFormDemo\obj\Debug\NotRepeatOpenFormDemo.FrmMainStaff.resources