[DiapDealer]

I'm not really the one for giving detailed instructions on using the Linux gdb command-line debugger. My teaching skills are not great. As for learning Sigil's code; everyone's different. There's no shortcut for getting your head wrapped around a million+ lines of code. You just need to dive in somewhere. I learned it in small chunks by studying the code in relation to a very particular aspect I wanted to change, or a very particular bug I wanted to locate/fix. Lots of individual little pictures, rather than trying to grasp the whole picture at once.

If you get lost looking for where something in particular happens in Sigil's code ... ask.