has a comfortable plug-in interface, giving access to e.g. the selected text, the handle to the RichEdit control, etc.
Attached the CompileBasic plugin for compiling sources written in a dozen BASIC dialects, plus some C/C++ variants. Extract to \Masm32\MasmBasic\Plugins; after a restart of RichMasm, the plugin will be in the System & Plugins menu. From then on, you can just paste a source code in RichMasm, then hit Ctrl F5 to compile it (provided the paths are set correctly, see CompileBasFiles.ini).
Once your source compiles correctly, a simple F5 will be sufficient. You can always use Ctrl F5 to see the dialog and change any commandline settings.