multiple designer plugin in one DLL.

[wysota]

Your issue is not related to Designer. The problem is that your application has to link with the code of the widget you are trying to use. And to do that, the library has to be found by the dynamic linker not only at compile time, but also during run time. You have to place the library in a path where linker will be looking for it. You can use the LD_LIBRARY_PATH variable to extend the linker lookup path if you need to.