We are developing our own UI type editor. The values set in the type editor are written on the resource files (.resx).

The object type on own type editor is dictionary<string,object>,

How can I set the property of a control in the Type Editor at design time (.designer.cs)?

Similar to your approach for StrataFrame.

There are a lot of articles, especially on Code Project, that can help you get started here.  This is more of a tutorial question and the web has a lot of great developer sites that have these already up and have step-by-step instructions.  If you don't find anything then let me know.