The screenshot shows the compiler window of the RexExTester application. This window is implemented as auxiliary - i.e. non modal - window that allows you to test regular expressions in one window and edit the compilation project in the other. The main idea behind compiled regular expressions is to increase evaluation performance. The assemblies are produced using the "CompileToAssembly" method of the "RegEx" class. Optionally you can specify a strong name key file (*.snk) to create a strong named assembly required for referencing it from other strong named assemblies.
Common assembly attributes like copyright or trademark attribute can be assigned as well but the current version will not add a Win32 resource to the assembly.