Rewrote a lot of the components tree code:

- Added SF_PSELECTED for partially selected sub-sections
- SF_EXPAND now refreshes the components tree
- Fixed problems with sub-sections with RO sections as children
- (-1) sent to .onMouseOverSection when mouse over nothing
- RO sections can now be in InstTypes too (default to old behavior)
- Optimized code


git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@2436 212acab6-be3b-0410-9dea-997c60f758d6

Contrib/Modern UI/System.nsh

@@ -229,6 +229,10 @@
   FindWindow ${MUI_TEMP1} "#32770" "" $HWNDPARENT
   GetDlgItem ${MUI_TEMP1} ${MUI_TEMP1} 1043
 
+  StrCmp $0 -1 "" +3
+    SendMessage ${MUI_TEMP1} ${WM_SETTEXT} 0 "STR:"
+    Goto mui.description_done
+
   !ifndef MUI_NOVERBOSE & MUI_MANUALVERBOSE
     !verbose 4
   !endif