问题
I just upgraded the Infragistics controls on a project from 2006 to 2011.
Now, if I open the designer for a form containing any Infragistics controls, the Infragistics controls appear in a separate panel underneath the form designer, and I am unable to select their counterparts in the design view.
If I click on an Infragistics control in the designer, it select the container control instead.
However, if I click the control in the lower panel, I can still edit the properties, and Visual Studio recognizes it as a UltraCombo. Also, the controls all still appear in the Toolbox, but if I try to add a new one to the form, it goes to the lower panel.
My coworker installed the new version of Infragistics on his computer and got my latest changes from source control, and he does not have the issue.
My issue sounds similar to this question Strange Design Problems With Infragistics Controls however the OPs reference material is no longer available.
回答1:
Answering my own question since I fixed it before submitting the questions to SO.
In short, it was my project references...
I decided to check out my project references as mentioned in the other question. I was pointing to copies of the DLLs that were not in the GAC. I changed the references to point to the GAC and all was well.
The reason I was pointing to non-GAC DLLs is: I like to keep DLLs in a source controlled "lib" folder that is in the same folder structure as the project. That way other developers can just grab the latest and they have all the correct versions of the DLLs that they need for the project and don't have to worry about installing them just to do a minor build. Apparently, the Infragistics library does not like that. My guess is it has to do with licensing. It's strange though, my computer was licensed, but the non-GAC DLLs didn't work.
来源：https://stackoverflow.com/questions/16320746/cannot-select-infragistics-controls-in-winforms-designer