This is an old one, but it's annoyed me plenty of times by now:
The templates for the Inline Function editor are indented with tabs, but the editor itself will use 4 spaces instead.
This means anything added to the template under "main" will be offset by one space.
Ironically, the templates for plugins("VATestPlugin" and "VATestPlugin_VB") are actually indented with 4 spaces.
Personally I prefer tabs, as I feel that gets far less messy.