combobox实现下拉框多选

C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\bin\Debug\DemoApp.exe C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\bin\Debug\DemoApp.pdb C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\bin\Debug\CheckBoxComboBox.dll C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\bin\Debug\CheckBoxComboBox.pdb C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\ResolveAssemblyReference.cache C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\DemoApp.Form1.resources C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\DemoApp.Properties.Resources.resources C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\DemoApp.csproj.GenerateResource.Cache C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\DemoApp.exe C:\Users\90349.OA1\Desktop\CheckBoxComboBox\DemoApp\obj\Debug\DemoApp.pdb