FS2004/FSX
To get all feedback from the compiler you would need to compile XML, SCASM or ASM files from the command prompt, but not every user feels so familiar with that. CompilerHelper is a tool that bridges that gap. It allows you to drag and drop files as you are used to, but it will still present you the feedback you would get from the command prompt.
Latest version
The latest release of Compile Helper is version 2.0. Click here to download this version.
Manual
You can find the Library Creator XML manual on the FSDeveloper Wiki.