As far as i understand it
Basic4GL is a BASIC programming language that supports Plugin DLL's "created in C++ with the plugin SDK".
On their website* is says that the plugin SDK "Includes project files for Microsoft Visual C++ 2005 and CodeBlocks."
So it is safe to assume that Codeblocks cam compile plugins for BASIC4GL, because they specifically included the project files for it.
For specifics on how to do that you may be better asking on their forums.
If you are asking for plugins for programs MADE in BASIC4GL I think that would depend on the specific program.
-Is CodeBlock a compiler and text editor united programming tool ?
Being an IDE I think the answer to your question is Yes, you can type up the program and compile it all from within codeblocks.
I hope this answers some of your questions.
*http://www.basic4gl.net/