It seems that the QT file qsvgicon4.dll is needed for svg icons in lyX. QtXml might be necessary as well
${FILE}QtCore4.dll"
${FILE}QtGui4.dll"
${FILE}QtSvg4.dll"
+ ${FILE}QtXml4.dll"
!macroend
!macroend
+!macro FileListQtIconengines COMMAND DIRECTORY
+
+ ${FILE}qsvgicon4.dll"
+
+!macroend
+
!macro FileListMSVC COMMAND DIRECTORY
# Manifest not needed for 2010
!insertmacro FileListLyXBin File "${FILES_LYX}\bin\"
!insertmacro FileListQtBin File "${FILES_QT}\bin\"
!insertmacro FileListQtImageformats File "${FILES_QT}\plugins\imageformats\"
+ !insertmacro FileListQtIconengines File "${FILES_QT}\plugins\iconengines\"
!insertmacro FileListDll File "${FILES_DEPS}\bin\"
!insertmacro FileListMSVC File "${FILES_MSVC}\"
!insertmacro FileListNetpbmBin File "${FILES_NETPBM}\"