Two bugs
I think I found two bugs in the latest CVS of NSIS.
1) If you use MUI and call !insertmacro MUI_LANGDLL_DISPLAY to display the language selection dialog in the .onInit method, you can't use language strings (LangString) in .onInit after that macro. A messagebox for example always uses the last LangString and doesn't care about the language selection the user made before.
If you call the messagebox in another method it works well. Please change that or at least add a notice to the documentation of the MUI that language specific functions doesn't yet work in .onInit.
2) The compiler displays a warning if you use LicenseText in MUI:
LicenseText: specified multiple times, wasting space (LangStrings.nsi:99)