SUGGESTED FIX

The last webrev is in http://sa.sfbay.sun.com/projects/awt_data/dolphin/6461933/
                                     

EVALUATION

Provided patch supposes a more frequent time update. Actually that doesn't needed so often. We may track the WM_TIMECHANGE message and adjust the boottime accordingly. In other words we may execute the same code if only NTP update just happened. 
I verified that mentioned event is heard by the Java application on NTP update. On WIndows XP(and further) there is a built-in NTP client. See DateTime->InternetTime->UpdateNow.

I'm introducing one more function nowMillisUTC(offset, updateBootTime) that may update boottime if the second parameter is TRUE. This would only be called from WM_TIMECHANGE handler. All other calls will address the it with the FALSE value.
                                     

SUGGESTED FIX

*** /tmp/geta24136	2006-12-15 13:31:49.000000000 +0300
--- awt_Component.cpp	2006-12-15 13:31:44.000000000 +0300
***************
*** 1759,1764 ****
--- 1759,1768 ----
            mr = WmPaste();
  	  break;
  
+       case WM_TIMECHANGE:
+           nowMillisUTC(GetMessageTime(), TRUE);
+           break;
+ 
        case WM_TIMER:
            mr = WmTimer(wParam);
            break;
***************
*** 2285,2291 ****
--- 2289,2300 ----
      }
      return nowMillisUTC(event_offset);
  }
+ 
  jlong nowMillisUTC(DWORD event_offset) {
+     return nowMillisUTC(event_offset, FALSE);
+ }
+ 
+ jlong nowMillisUTC(DWORD event_offset, BOOL updateBootTime) {
      // All computations and stored values are in milliseconds. The Win32
      // FILETIME structure is in 100s of nanoseconds, so the FT2INT64 macro
      // divides by 10^4. (10^7 / 10^4 = 10^3).
***************
*** 2319,2325 ****
      SystemTimeToFileTime(&current_sys_time_1601, &current_file_time_1601);
      current_time_1601 = FT2INT64(current_file_time_1601);
  
!     if ((current_time_1601 - boot_time_1601) > WRAP_TIME_MILLIS) {
          // Need to reset boot time
          DWORD since_boot_millis = GetTickCount();
          boot_time_1601 = current_time_1601 - since_boot_millis;
--- 2328,2334 ----
      SystemTimeToFileTime(&current_sys_time_1601, &current_file_time_1601);
      current_time_1601 = FT2INT64(current_file_time_1601);
  
!     if (((current_time_1601 - boot_time_1601) > WRAP_TIME_MILLIS) || updateBootTime) {
          // Need to reset boot time
          DWORD since_boot_millis = GetTickCount();
          boot_time_1601 = current_time_1601 - since_boot_millis;
                                     

EVALUATION

According to the code we do following things:
1)get BootTime
2)get current system time
3)if (current system time - BootTime) >49.7 days then do (4) and (5)
4)  get the time length passed since system boot by getTickCount() call
5)  update BootTime accordingly
6)return BootTime+event_offset

That happens usually just after the application starts and there is no problem with it.
Now lets imagine that the first initialization had passed and after some time we get an NTP update.
AWT itself updates the BootTime every 49.7 days after boot. NPT is also changing the BootTime value but AWT does nothing for that case because we think that there is not so much time had passed yet.
                                     

EVALUATION

Sounds reasonable. Should consider a performance impact as well.